The Evolution from Diesel to BLUETEC in Depth

Press Release

• Diesel technology from Mercedes-Benz: A history of innovations
• From stationary engine to refined automotive drive
• BLUETEC: The diesel technology of the future

The diesel engine draws much of its appeal from the history of the Mercedes-Benz brand. It "learned to walk" in the motor vehicle at Benz & Cie. - at the beginning of the twentieth century, design engineer Prosper L'Orange developed a vehicle propulsion unit from Rudolf Diesel's engine, and in 1923 the world's first diesel truck originated in Mannheim. Finally, in 1936 Mercedes-Benz built the world's first diesel passenger car. Since that time there has been an unending succession of innovations to every aspect of the compression-ignition engine in the vehicles of the Stuttgart-based brand.

BLUETEC is the latest innovation for low emission levels and is going to further advance the powerful but low-emission drive towards the future. These high-tech vehicles, which make good ecological sense and are blessed with attractive driving qualities, provide an answer to the questions of the vehicle concepts of tomorrow. In the modular BLUETEC system, Mercedes-Benz has put together a technology package for coming vehicle generations.

Its foundation is the diesel history of the brand. Over decades, the diesel increasingly has become a clean, powerful, high-speed drive unit, yet has retained its economical nature. Originally it was this economic efficiency and robustness which impressed contemporaries; today the diesel engine is an extremely low-emission power plant with sporty characteristics. Consequently, in the face of increasingly stringent emissions standards, the current compression-ignition engines constitute an alternative to gasoline engines more than they ever did. The market reflects this development: in the meantime every second car sold in Western Europe is a diesel car. Mercedes-Benz even sells 54 percent of its cars with a compression-ignition engine under the hood. The diesel is coming on very strong. Rudolf Diesel and his invention

A far-sighted engineer

Rudolf Christian Karl Diesel was born on March 18, 1858 in Paris. At the tender age of 14 the son of a bookbinder decided on a career as engineer. After attending trade school and industrial school he went to Munich Technical University (Polytechnic Institute) and concluded his studies in 1880 with the best grade ever given for an examination since the university was founded. During his education in the engineering sciences the design engineer-to-be was particularly impressed by the thermodynamics lectures of Carl von Linde.

The contact with Linde had consequences: after completing his studies, Diesel went to work in the Linde refrigerating machine factory. But most of all, animated by Linde's lectures he decided to develop a new engine featuring especially good thermal efficiency. In 1881, after a one-year period of traineeship, the young engineer was hired to work in Linde's ice factory in Paris. Before the year was over, Diesel received a first patent for the manufacture of transparent ice.

During the following years, Rudolf Diesel increasingly focused on the work on his engine. In 1892 he took out a patent for his concept of a "new, rational heat engine"; patent DRP 67 207 "on a principle of operation and construction for internal combustion engines" was granted on February 23, 1893. In November 1893 Diesel modified and improved his first design and took out a second patent (DRP 82 168).

At Augsburg Machine Works (later MAN), from 1893 on Diesel developed a prototype and had the first test engine running within a few months. But it would take four years from the beginning of work to design a successful prototype of an engine fit for series production. The Augsburg diesel engine factory was built in 1898 to produce the new power plant.

1897 - The diesel engine

Whereas the spark-ignition engine compresses a mixture of air and fuel, Diesel's engine was supposed to compress the intake air, into which the fuel would be injected just before ignition - that was what the engineer had in mind. Subsequent to this mixture formation, which takes place entirely inside the cylinder, the fuel ignites spontaneously due to the heat produced by compression. On paper, Diesel's calculations for this process achieved extremely high compression pressures of as much as 253 bar; in reality, the pressures remained substantially below this level.

But considering that temperatures between 700 and 900 degrees Celsius were obtained by the compression of air in the cylinder, this fully sufficed to operate the new-type engine: with its very good ignition qualities, the diesel oil needed no additional starting aid to burn at these temperatures shortly after being injected. Before Rudolf Diesel finally decided on a middle distillate of petroleum as fuel, he experimented with various other substances. In one test he used coal dust. However, the first prototypes then ran on kerosene, which is similar to diesel oil in many respects.

Compared with the gasoline engine, the diesel engine has very good efficiency especially at partial load. It was this efficiency which convinced the first buyers of the new engine around 1900 - despite public criticism of Diesel's concept. But the early engines did not prove durable enough yet, and many customers returned their damaged engines. Particularly, the air compressor and the strainer-type atomizer used for fuel injection were susceptible to mechanical trouble. The inventor reacted by developing a new atomizer and improving the compression of the injection air by dividing compression into two phases.

The supply of fuel to the engine still called for a complicated process: a low-pressure pump delivered the fuel to the atomizer; from here, strongly compressed air blew the diesel oil into the cylinder as a fine fuel mist. This technology made the engines heavy and complex. Higher engine speeds and reaction to changing loads were impossible.

Rudolf Diesel's development efforts repeatedly were hampered by technical misunderstandings. Among other things, at the beginning of his work the engineer thought the spontaneous inflammation of the fuel was not vital, and he experimented also with sparkplugs. But the very first prototype of 1897 showed that the basic principle of this internal combustion engine had a great future: Diesel's engine established it-self alongside the gasoline engine as second type of internal combustion engine, though originally only in the form of a stationary engine.

All modern-day vehicular diesel engines follow the basic principle of these engines. However, Rudolf Diesel's simple basic design has long since evolved into a technically sophisticated engine system. Solutions like common rail injection with injection pressures of up to 2,000 bar, exhaust-gas turbocharging and ultramodern emission control systems have made the diesel a powerful, economical, clean vehicle drive.

From stationary engine to marine diesel

Once Diesel had refined his concept to the point where it could be marketed, Augsburg Machine Works discontinued the production of steam engines in the course of the next few years and concentrated entirely on the manufacture of diesel engines. This step was quite in keeping with the market trend: the diesel engine, powerful competition for the steam engine, prevailed and superseded the steam engine. Between 1907 and 1909 alone more than 1,000 units with outputs from 15 kW to 74 kW (20 - 100 hp) were produced. But as a propulsion unit for transport purposes, prior to the First World War the new engine only saw use in ships, beginning in 1903.

Rudolf Diesel did not live to see the success of his engine as a propulsion unit for road and rail vehicles. The inventor, faced with financial ruin, disappeared from the postal steamship "Dresden" during a crossing from Holland to England in 1913. It is considered probable that the engineer committed suicide. Still, Diesel foresaw the potential of his technology: "I am firmly convinced," he wrote in 1913, the year of his death, "that the automobile engine will come, and then I consider my life's work complete."

1910 - Marine diesels from Benz and Daimler

Benz and Daimler too built diesel engines for watercraft at the beginning of the twentieth century: Benz & Cie. delivered their first two four-stroke marine diesel engines in 1910. In September 1911 Benz then introduced a two-stroke diesel drive for marine use. This engine, "Patent Hesselman," was based on a Swedish power unit which Aktiebolaget Diesels Motorer in Stockholm had been building since 1907. The "Fram", an expedition and research vessel, was one of the ships equipped with the Benz two-stroke engine. The "Fram" was built back in 1892 for the Norwegian polar explorer Fridtjof Nansen. It served as an expedition vessel from 1893 until 1912. Roald Amundsen had the 132 kW (180 hp) Benz diesel installed for his journey to the South Pole from 1910 to 1912.

In September 1911, Daimler-Motoren-Gesellschaft (DMG) received an order for ten four-stroke air-injection marine diesels with an output of 74 kW (100 hp). The RM 20 274 engines were manufactured in DMG's Berlin-Marienfelde factory; the first five units were delivered by Daimler in 1912.

Both companies also manufactured engines for submarines in the First World War. In January 1916 the DMG Marienfelde factory won a contract for twelve 221 kW (300 hp) six-cylinder diesel submarine engines. The first seven units of this model MU 256 were supplied to the customer in the same year. During this period Benz & Cie. also worked on powerful diesel engines for submarines, building eight S 6 Ln six-cylinder engines, each with 331 kW (450 hp), between 1915 and 1916.

From ship to road

The diesel engine was not ready for the step from stationary and marine use to installation in the automobile until after 1920. The engineering achievement which this development represents was the work of Prosper L'Orange, an engineer working for Benz & Cie since 1908. In Mannheim he devoted himself to making Rudolf Diesel's dream reality: the compact, high-speed diesel engine as an automotive power unit. L'Orange developed prechamber injection, the pintle-type injection nozzle, the funnel prechamber and the variable injection pump - milestones on the compression-ignition engine's way into the automobile and at the same time the basis for the first vehicle diesel engines.

A life for engine technology

Prosper L'Orange was born on February 1, 1876, in Beirut, in the then Ottoman Empire. He grew up in Germany after 1890. The boy was very enthusiastic about the technology of internal combustion engines and decided to attend the Technical University in Berlin-Charlottenburg. He passed his diploma examination cum laude and became an assistant to Privy Councilor Emil Josse in the university's heat technology laboratory.

L'Orange went from there to Gasmotorenfabrik Deutz, where he became head of the testing department in 1906. Here he worked mainly on a diesel engine variant which did not have a compressor for air-injection of the diesel oil. He planned to transfer the principle of this internal combustion engine to smaller engines: compact units with around 26 kW (35 hp) would make ideal power plants for automobiles. However, L'Orange realized that the engine first had to be cured of the "lack of restraint of its fuel feed." He intended to devise a solution which would enable controlling fuel atomization, and thus combustion, more accurately than before.

Similar projects were pursued by other engineers too, but Prosper L'Orange took the most forward-looking approach with his injection pump. This precision-controlled instrument delivered fuel to the combustion chamber under 50 atmospheres of pressure. The engineer then turned to the shape of the compression space to improve the mixing of compressed air and fuel spray: in 1908 L'Orange took out a patent on a so-called afterchamber, a space before the cylinder in which air and fuel could swirl. The uncooled, spherical chamber was placed opposite the combustion chamber, with inlet and outlet valves arranged between the two. After the fuel was injected, a small amount of diesel fuel was ignited in the afterchamber; this ensured good swirling of the remaining fuel in the compressed air of the combustion chamber proper. Compared with the usual solution up to then - the use of a compressor to inject atomized fuel - L'Orange's new engine with injection pump and afterchamber was appreciably more compact. But the Deutz diesel engines still were too heavy for fitting in vehicles.

After moving along to Benz & Cie. in Mannheim, with a series of innovations between 1908 and 1922 Prosper L'Orange developed the heavy oil engine further into a high-speed power unit for vehicles. The engineer's most important improvements during this period were the prechamber principle, the funnel prechamber, the pintle-type injection nozzle, and finally the variable injection pump. However, L'Orange left Benz & Cie. in 1922 before the first diesel truck was introduced, becoming the head of stationary engine manufacture at Motoren-Werke Mannheim (MWM), which had emerged from Benz & Cie. From 1926 he worked as a free-lance engineer, and in 1927 he took over the management of the firm REF-Apparatebau GmbH in Stuttgart-Feuerbach. In 1932 REF-Apparatebau went bankrupt. L'Orange was honored for his lifework in 1939 with an honorary doctorate from Karlsruhe Technical University. The father of the modern diesel engine died on July 30, 1939, in Stuttgart.

1909 - The prechamber

In 1908 Prosper L'Orange was hired by Benz & Cie. as head of engine testing. In Mannheim the engineer's aim was mainly to improve the diesel principle, as he had done at Deutz. With his afterchamber diesel he had already taken a first step towards splitting mixture formation and the combustion chamber. Now he experimented on an improvement to the shape of the cylinder head. For this work L'Orange designed a test engine that could be fitted with different cylinder heads.

On this engine he also tried out a variant in which a semispherical chamber was arranged between the injection nozzle and the cylindrical combustion chamber. In this space, which occupied 20 percent of the total cylinder volume, after injection a small portion of the diesel fuel burnt upon contact with the hot chamber wall. This created an extremely high pressure in the prechamber, driving the remaining diesel-air mixture into the cylinder and ensuring very good mixing there due to the turbulence of the compressed intake air. Pressure and mixing enabled rapid combustion at high temperatures. With the prechamber diesel, therefore, appreciably higher engine speeds were possible than with older forms of the compression-ignition engine.

In a first test run, the prechamber diesel proved robust, reliable, and above all economical. The engine continued to cause problems for its designer, not the smallest of which was that it was still too big to be installed in an automobile. But Prosper L'Orange knew he was on the right track in his work: on March 14, 1909, he submitted a patent application for the prechamber system (DRP 230 517). L'Orange was rewarded for his success by Benz & Cie. by being given the position of an authorized officer in the stationary engine construction unit in 1910.

1919 - Funnel prechamber, pintle-type injection nozzle and variable injection pump

The First World War put a stop to the further development of diesel technology at Benz & Cie. In 1915 the Mannheim people even gave up the prechamber patent entirely. So when L'Orange resumed the work on a modern diesel engine after the war's end, he not only remembered his own groundwork, but also examined other new concepts. He happened upon the Swedish Ellwe diesel engine with semispherical prechamber and bores connecting it with the combustion chamber. Spurred by the competitor's development, L'Orange continued improving his own prechamber. With a funnel-shaped insert between pre-chamber and combustion chamber he changed its shape to achieve reliable ignition and good combustion under different loads. Among other things, the new shape favorably influenced the vaporization of the diesel oil and reduced the risk of carbon deposits. He applied for a patent on this modification on March 18, 1919 (DRP 397 142). Parallel to this he was working on a new injection nozzle that worked much better than earlier variations. Prosper L'Orange also introduced this pintle-type injection nozzle in 1919.

In 1921 a variable injection pump for the diesel engine followed. Its delivery quantity could be infinitely varied, and it finally enabled the engineer to regulate the power output of the engine with the precision required for use in automobiles. The first installation of a high-speed diesel power unit in a vehicle was now only a matter of time. Debut of diesel engines in tractors and trucks

1922 - Benz diesel for agriculture

The first land vehicle the Benz diesel engine saw use in was a tractor in 1922. The Mannheim firm developed the three-wheeled vehicle together with the Munich engine and tractor maker Sendling. Benz and Sendling displayed the prototype at a 1922 agricultural exhibition in Königsberg, today Kaliningrad, and immediately found buyers for this vehicle and two more preproduction series units. The machine was equipped with a two-cylinder diesel which developed 18 kW (25 hp) at 800 rpm. Bore and stroke: 135 x 200 millimeters. The tractor went into production in March 1923 as the Benz-Sendling S 6 motor plow with one driving wheel.

Benz & Cie. initially planned to manufacture 100 engines for Sendling tractors and motor plows. But by late 1924 they had already manufactured and sold 36 two-cylinders. Through 1931 the Mannheim people, later under the umbrella of Daimler-Benz, produced a total of 1,188 of these engines. In addition to the three-wheeled tractor and motor plows, from 1923 on Benz-Sendling offered the four-wheeled BK diesel tractor model.

1923 - The world's first diesel truck from Benz & Cie.

Benz & Cie. presented the world's first diesel truck in 1923. The five-tonner was powered by a four-cylinder diesel designated OB 2, with 33 kW (45 hp) at 1000 rpm. In direct comparison with a gasoline-powered truck of identical design, the diesel truck impressed right off with its economy: the compression-ignition power unit yielded fuel savings of 86 percent versus the spark-ignition engine.

Work on the new engine for the truck already began in 1922. In September of that year the first engine was running on a test bench. Initially, ten OB 2 engines were built. With four cylinders with a bore of 125 millimeters and a stroke of 180 millimeters, the engine produced around 33 kW (45 hp) at a rated speed of 1000 rpm. Test drives with the first production diesel were carried out from Gaggenau. The Benz engineers chose the Benz 5 K 3 truck as chassis, designed for a pay-load of five tons. The OB 2 made such a good showing in the road tests that the decision to build it in series was already taken on April 14, 1923. The world's first series-built diesel truck finally debuted at the commercial vehicle show in Amsterdam in February 1924. By then the prechamber diesel engine OB 2 had an output of 37 kW (50 hp) at 1000 rpm.

Particularly impressive its low fuel consumption: running on tar oil distilled from brown coal, the OB 2 needed about a quarter less fuel than an equally powerful gasoline engine. Due to the low price of tar oil compared with gasoline, the result was sensationally low fuel costs. In addition to tar oil, the engine also could operate on "gas oil, kerosene, Texas oil as well as yellow or brown paraffin oil" - said a 1923 Benz & Cie. advertising blurb for the frugal power plant.

1923 - Air-injection diesel truck from Daimler

While Benz & Cie. were developing the diesel truck, in Berlin-Marienfelde Daimler-Motoren-Gesellschaft (DMG) was designing an almost equally powerful air injection diesel to be fitted in trucks. The Daimler engineers applied their knowledge from the manufacture of air-injection diesel engines for submarines to this engine and created a four-cylinder unit delivering 29 kW (40 hp) at 1000 rpm. The engine proved its practical suitability on a number of test runs in 1923. One very spectacular run was a long trip between two DMG plants: between September 20 and 30, 1923, a Daimler diesel truck drove from Berlin to Stuttgart and back.

1927 - The prechamber diesel prevails

However, after the merger of Benz & Cie. and DMG in 1926 the Benz prechamber principle prevailed over the air injection diesel. The first jointly developed prechamber engine was the six-cylinder OM 5 of 1927 (55 kW/75 hp from a displacement of 8.6 liters). The designation "oil motor" (OM) for diesel engines has survived since then in the Mercedes-Benz nomenclature.

The Mercedes-Benz L 5 truck operated alternatively with the new OM 5 (51 kW/70 hp at 1300 rpm) or an M 36 gasoline engine (74 kW/100 hp at 2000 rpm). The five-tonner (a low-frame version called the N 5 also could be had) was the sole diesel-powered model in the new Mercedes-Benz commercial vehicle range presented in 1927. Both the 1.5-ton truck and the 3.5-ton truck initially were available only with gasoline-fired carburetor engines - a Mercedes-Benz concession to the still considerable skepticism of customers towards the diesel engine.

The OM 5, regular production of which started up in 1928, was already fitted with the new Bosch injection pump. Robert Bosch began working on diesel injection pumps in 1922. With the systematically improved injection technology introduced in 1927, Bosch contributed to getting the diesel drive accepted. Bosch himself did not have to be convinced of the compression-ignition engine's qualities: in 1924 he was one of the first customers to order a diesel truck from Benz & Cie.

Diesel engines in Mercedes-Benz passenger cars: 1926 - 1995

1926 - The early history of the Mercedes-Benz 260 D

Mercedes-Benz held a sensation in store at the February 1936 International Automobile and Motorcycle Show in Berlin: in the model 260 D (W 138 series) the diesel engine swept into the passenger car world. In the year of the Olympic Games the Stuttgart company introduced this model as the world's first production diesel car. It was equipped with a four-cylinder engine with a Bosch injection pump which permitted higher engine speeds and speedier fuel supply. The 2.6-liter unit had a compression ratio of 20.5:1 and delivered 33 kW (45 hp) at 3200 rpm. The first diesel car in the world was the result of intense research which began upon the merger of DMG and Benz & Cie. in 1926. The first thing done by the young Daimler-Benz AG was to design a new six-cylinder diesel engine for trucks. The power plant was steadily improved. Its output and engine speed rose: in the early 1930s, the diesels already managed 2000 rpm.

Over the coming decades the engine speed especially of car diesel engines would be continuously boosted. However, compared with the spark-ignition gasoline engine the compression-ignition engine has a physically determined speed limit of around 5500 rpm - a result of the delayed ignition of the fuel. The time that passes between injection and ignition is appreciably less with modern-day diesel fuels than with the old diesel oil, which was chemically identical with fuel (heating) oil. The cetane rating indicates the quality of the diesel fuel. The higher it is, the quicker the fuel ignites.

1934 - Four-cylinder diesel for cars

A high engine speed was an important condition for adopting the diesel in cars. For its premiere the compression-ignition engine had to come as close as possible to the gasoline engine. However, diesel engines were still much heavier and less smooth than gasoline engines. And so the first test diesel engine for a car, a 3.8-liter six-cylinder developing 60 kW (82 hp) at 2800 rpm, promptly proved too rough for the chassis of the test car because of its strong vibrations.

It was followed by several test engines, such as the OM 134 - a water-cooled three-cylinder diesel with 22 kW (30 hp) - which was installed in the Mercedes-Benz 160 V car in 1934. The six test cars (W 134 series) received the model designation Mercedes-Benz 175 D and were available with sedan as well as convertible B and C bodies. However, the vibration problems of the three-cylinder proved to be uncontrollable. In the same year, therefore, four test cars of the 175 DX model (W 141 series) were set up and fitted with four-cylinder engines (OM 141, 26 kW/35 hp). The engineers undertook further diesel tests in models which included the Mercedes-Benz 130 H and the Mercedes-Benz "Mannheim."

In November 1934 the Mercedes-Benz engineers then opted for a different approach and, instead of an entirely new development, banked on modifying the proven six-cylinder of commercial vehicle provenance. For operation in passenger cars the engine was reduced to the size of a four-cylinder with a displacement of 2.6 liters. The smooth combustion permitted by the prechamber principle meanwhile had been perfected, among other things through the use of a four-plunger injection pump from Bosch. The four-cylinder already had overhead valves, a very modern feature, and developed its maximum output of 33 kW (45 hp) at 3000 rpm. A crankshaft running in five bearings contributed effectively to vibration damping and, in addition, permitted high revolving speeds. The engineers had finally reached their goal.

1936 - Darling of taxi operators

Assembly-line production of model 260 D began in 1935. The OM 138 was installed in the chassis of the Mercedes-Benz W 21 series. The resultant Mercedes-Benz 260 D consumed an average of 9.5 liters of diesel fuel per 100 kilometers (24.7 mpg) - the closely related model 200 guzzled 13 liters of gasoline over the same distance. The 260 D traveled 450 - 500 kilometers on one tank filling - quite an asset given the rather wide-meshed gas station network at the time. What's more, a liter of diesel cost 24 pfennigs in Germany - clearly less than a liter of gasoline for which 39 pfennigs had to be paid. And anyone working as a taxi driver with a passenger transport license was able to buy diesel at a reduced price of 19 pfennigs per liter. With a top speed of 90 km/h (56 mph), despite all economy the Mercedes-Benz 260 D traveled at a fairly brisk pace - even the 200 managed only 98 km/h (61 mph).

The world's first diesel passenger was built on the chassis of the W 21-series landaulet (Mercedes-Benz 200 and 230). The sales brochure proudly extolled the combination of modern passenger car and diesel technology: "It is natural that Daimler-Benz A.G., in view of its great successes in the fields of passenger car and diesel commercial vehicle manufacture, also deeply concerned itself with the question of the passenger car diesel engine. The result is the Mercedes-Benz model 260 D […], which combines the great advantages of the diesel engine with the obvious comforts of the swing-axle passenger car."

The first 170 vehicles already were delivered in the fall of 1935 before actual series production began in 1936. The 260 D quickly gained acceptance as the ideal taxi. Cheap to maintain, robust and long-lived engines, a spacious body (also in a special taxicab version with up to seven seats): these were the arguments with which the new Mercedes-Benz convinced the taxi trade. Engine-powered cabs based on the 260 D were still widespread far into the 1950s. Also, the 33 kW (45 hp) 2.6-liter diesel powered the van models L 1100 to L 1500, which were built in Stuttgart and Mannheim.

1937 - Diesel cars for private customers

Contemporaries were favorably impressed how quiet this diesel car was. Private customers too let themselves be convinced by the virtues of the Mercedes-Benz 260 D and bought the car with the compression-ignition engine - especially after the engine was worked over in 1937 and the model got a new body.

The Mercedes-Benz W 143 series served the 260 D as new chassis beginning in 1937. Two- and four-door convertibles and an open touring car were added to the landaulet and Pullman limousine. Through 1940 some 2,000 units of the world's first diesel car were built - not a large number, but enough to make the diesel-powered car acceptable and smooth its way in the postwar period. Thanks to the farsightedness of its creators and above all the continuity of its further development, the diesel car has captured a firm spot in the Mercedes-Benz model range.

1949 - New beginning with the 170 D

Following the end of the Second World War, economic automobiles were more than ever in demand. Mercedes-Benz again included a four-cylinder car diesel engine in the model range in the form of the model 170 D (W 136 series). The 170 was largely identical with the Mercedes-Benz 170 V built from 1936 to 1942. The diesel variant launched in 1949 was powered by the 1.8-liter OM 636 I engine, an in-line four-cylinder diesel developing 28 kW (38 hp) at 3200 rpm. As early as 1950 Mercedes-Benz introduced a modified power plant that now had an output of 29 kW (40 hp). The sedan's top speed increased from 100 km/h to 105 km/h (65 mph).

The first 170 D was handed over to its buyer on August 1, 1949. In the following years many more customers in industry, the trades and the public sector, but also private individuals, chose the first postwar Mercedes diesel. From 1949 to 1953 a total of 33,822 units of the model were built, including chassis and half-ton panel vans.

The more comfortable, advanced version of model 170, the 170 S, also had a diesel-powered variant. The Mercedes-Benz 170 DS (W 136 VIII D series) came out on the market in 1953 and was built until 1955. The 170 DS was equipped with the 29 kW (40 hp) OM 636 VIII. To cut the higher production price of this diesel engine versus the gasoline drive, the OM 636 was manufactured in very large numbers and not only used in models 170 D and 170 DS, but also in the Unimog. Daimler-Benz AG also sold the unit as a stationary engine.

1954 - "Ponton" Mercedes with diesel engine

Models 180 D (W 120 series) and 190 D (W 121 series) put the diesel drive in the wrappings of the "Ponton" (a self-supporting chassis-body structure) design introduced in 1953: aerodynamically optimized and featuring a unitary body. The familiar 29 kW/40 hp engine powered the 180 D on its debut in March 1954; in 1955 the output was raised to 32 kW (43 hp) at 3500 rpm. In 1958 Mercedes-Benz then introduced the new OM 621 engine. As a 1.9-liter diesel power unit it developed 37 kW (50 hp) at 4000 rpm in model 190 D; from 1961 it also propelled the 180 D with 35 kW (48 hp) developed at 3800 rpm. In all, 235,000 units of the two models were built.

The Mercedes-Benz "Ponton" with diesel engine also was exported to North America. To create awareness of the design, in 1954 journalist Bill Carroll undertook a test drive across the USA in a Mercedes-Benz 190 D. Mercedes-Benz diesel cars repeatedly have provided such demonstrations of reliability. In addition to long, strenuous journeys, records and outstanding sporting achievements have molded the diesel history of Mercedes-Benz. In 1955, for example, three Mercedes-Benz 180 D were the winners in their class in the Mille Miglia. Mercedes racing manager Karl Kling personally showed that the diesel drive is good for sporty performance. In a model 190 D he won the 1959 Africa Rally over 14,045 kilometers (8,728 mi.) from Algiers to Cape Town at an average speed of 80.6 km/h (50 mph).

1961 - Fintail 190 D and 200 D

In the "fintail" (W 110 series) the diesel further emancipated itself from its origins in the commercial vehicle. The two-liter diesel presented in 1961 was still called the 190 D. But when Mercedes-Benz introduced the new model 200 in 1965, the compression-ignition variant also was renamed 200 D. Its displacement and output (44 kW/55 hp at 4200 rpm) remained the same. In addition to a five-bearing crank-shaft the OM 621 four-cylinder diesel engine got better sound insulation than its predecessor and, as a high-speed diesel, propelled the car to a top speed of 130 km/h (81 mph). On the other hand, accelerating from standstill to 100 km/h still took 28 seconds.

From 1965 to 1968, 159,365 200 D sedans were built, plus units of the 200 D Universal station wagon and the 200 D with long wheelbase (3350 millimeters instead of 2700 millimeters) and eight seats. The diesel had become well established in the mid-sized range of Mercedes-Benz. This is shown by the sales figures and the model range diversification which took place in the late 1960s. And diesel-powered cars long since had ceased to be austere in their appointments: as an optional extra the compression-ignition models of Mercedes-Benz were now even available with an automatic gearshift.

1967 - Five-cylinder diesel in the Stroke Eight

In 1968, for the first time two new diesel models were introduced simultaneously, the 200 D and the 220 D, in the W 115 series. In 1973 the 240 D was added to the range, and in July 1974 the 240 D 3.0 appeared as the top-of-the-line model. It was powered by the world's first five-cylinder passenger car diesel engine. Even the injection pump and its controls were new on this new engine developed on the basis of the OM 616.

With a swept volume of 3,005 cubic centimeters, the OM 617, designed as an in-line five-cylinder, generated 59 kW (80 hp) at 2400 rpm and had a respectable top speed of 148 km/h (92 mph). With acceleration from standstill to 100 km/h in 19.9 seconds, the new top diesel model from Stuttgart was the liveliest and fastest diesel car in the world and featured impressive smoothness and economy. 53,690 units of the 240 D 3.0 were manufactured; in all Mercedes-Benz sold 945,206 W 115-series diesel cars.

The starting equipment of the five-cylinder diesel also was innovative: instead of the mechanical shutoff device of the 2.4-liter engine only a pneumatic device was used, so that the engine could be shut off with the ignition key. Starting was also by a turn of the key in the 240 D 3.0 and not, as previously was the case, by pulling a lever: when the driver turned the ignition key, preglowing was initiated and an indicator lamp lit up. When the light went out after a bit, the engine could be started in the normal way with a key. What now appears the most natural thing in the world was appreciated as a new comfort feature in 1974, which has since gradually found its way into all diesel cars of the brand and beyond.

1976 - Four diesel engines for the 123 series

The new mid-sized series took the start with four diesel variants in 1976. The W 123 came out as 200 D, 220 D and 240 D with four-cylinder engines and as 300 D with the in-line five. With that Mercedes-Benz took the entire, extremely successful diesel program of the Stroke Eight into the new model. For use in the W 123 the engines were thoroughly worked over. Among other things they were given new cylinder head gaskets made of a material called Ferrolastik; in addition, oil changes were made simpler; the exhaust system was improved and the oil and fuel filters modified.

In view of the big demand for diesel models both from the new series and the W 115 series, the compression-ignition Stroke Eight models continued to be built for one year parallel to the W 123. How popular the diesel model had become in the meantime is shown in the statistics: the biggest-selling sedans of the 123 series were the 240 D (448,986 units) and 200 D (378,138 units).

1977 - A diesel coupe improves CAFE

In the fall of 1977 the 300 CD diesel coupe was added to the 123 series. The engine of the two-door car was the same fitted in the 300 D sedan: the three-liter five-cylinder diesel OM 617 with its output of 59 kW (80 hp) at 4000 rpm. However, the elegantly styled diesel was manufactured exclusively for the North American market. The object was to improve the Corporate Average Fuel Economy of Mercedes-Benz automobiles in the US and Canadian markets.

CAFE describes the average fuel consumption of all models of a brand. Under a regulation issued by the US government, by 1985 the average consumption of all models of a car brand sold in North America had to be less than the equivalent of 8.55 liters per 100 kilometers (27.5 mpg). The number of units of each model sold was not important. CAFE was computed simply by adding up the average consumption of all variants on offer and dividing up this figure by the number of variants. Innovative concepts like the economical diesel engine in the 300 CD therefore made their mark on the consumption statistics.

1977 - A turbodiesel for the S-Class

Another diesel model presented by Mercedes-Benz specifically for the American market caused a stir at the 1977 Frankfurt International Motor Show (IAA): the 300 SD was the first S-Class (W 116 series) from Stuttgart to be equipped with a compression-ignition engine. An exhaust-gas turbocharger provided for performance appropriate to the luxury sedan, boosting the output of the five-cylinder diesel familiar from the 123 series to 85 kW (115 hp). In May 1978 production of the model based on the US version of the W 116 series began. The three-liter diesel was fitted with a Bosch injection pump and a Garret exhaust-gas turbocharger and provided the 1.8-ton sedan with respectable performance: the top speed was 165 km/h; the S-Class Turbodiesel sprinted from standstill to 96 km/h (= 60 miles an hour) in 14 seconds. The diesel cousin could not match the unbelievable performance of the 450 SEL 6.9 of the W 116 series. But it made up for it with an average consumption of only 14 liters of diesel per 100 kilometers (16.8 mph) , while the S-Class with the M 100 V8 engine required 22 liters of premium gasoline for the same distance (10.7 mpg) - albeit a very common con-sumption figure in those days.

1980 - Turbodiesel in the 123 series

The American CAFE standards were further toughened in the late 1970s. Accordingly, in 1981 Mercedes-Benz replaced the 300 CD and 280 C coupes from the 123 series with the new 300 CD Turbodiesel and also offered the 300 D Turbodiesel as a parallel model. Whereas these new models again were reserved for the North American market, the Mercedes-Benz 300 T Turbodiesel launched in 1980 was also sold in Germany.

Like the sedan and the coupe, this station wagon had the three-liter in-line five-cylinder under its hood, boosted by a Garrett exhaust-gas turbocharger. After debuting in the S-Class the engine now developed 92 kW (125 hp) at 4350 rpm and was good for a top speed of 165 km/h (102.5 mph) and acceleration from standstill to 100 km/h in 15 seconds. In all, 28,219 units of the first Mercedes-Benz turbo-diesel car for the German market were sold between 1980 and 1986.

With the turbodiesel models from the 123 series, the turbocharged compression-ignition engine returned to its origins in the test shops of Mercedes-Benz: the first turbodiesel engine designed by the Stuttgart engineers, with an output of 132 kW (180 hp), was installed in a 123 chassis for test driving. Following the successful tests with the prototype it was decided to pursue the concept further and develop a five-cylinder turbodiesel for the S-Class.

1983 - Whisper diesel in the new compact class (W 201 series)

As third car series, Daimler-Benz put the compact class on the market in 1982. The small Mercedes got a new two-liter diesel (53 kW/72 hp at 4600 rpm) in 1983 and was called the 190 D. The engine was designed as a lightweight, economical, agile unit. Above all, the engine was completely encapsulated, reducing the noise it generated by half. The OM 601 became known as the "whisper diesel." Mercedes-Benz supplemented this four-cylinder in 1985 with an in-line five-cylinder (66 kW/90 hp at 4600 rpm) installed in the 190 D 2.5. The top speed of the 190 D was 160 km/h (99.4 mph), while the more powerful 190 D 2.5 now did 174 km/h (108 mph).

Once again, models specifically intended for the North American market were created: the 190 D 2.2 of 1983 had a modified four-cylinder diesel engine, the 190 D 2.5 Turbo was based on the in-line five-cylinder of the 190 D 2.5. Exhaust gas turbocharging ensured an output of 90 kW (122 hp) at 4600 rpm, the top speed was around 192 km/h (119 mph). Starting in 1986, 20,915 units of this most pow-erful of the diesel models from the W 201 series were built in all. Originally designed as an export model, the 190 D 2.5 Turbo also was available in Germany from September 1987 on.

1985 - Six-cylinder compression-ignition engine in the 124 series

For the first time the mid-sized 124 series offered an in-line six-cylinder diesel engine in a Mercedes-Benz passenger car. At the presentation of the new models in December 1984, the Stuttgart automakers introduced the 200 D with four-cylinder power plant (53 kW/72 hp at 4600 rpm), the 250 D with five cylinders (66 kW/90 hp at 4600 rpm), and finally the 300 D with an in-line six-cylinder (80 kW/109 hp at 4600 rpm). The two-liter four-cylinder of the 200 D was known from the compact class. The 300 D was distinguished externally from the smaller models by additional air intake slots in the front apron.

In 1985 Mercedes-Benz launched the 300 D Turbo as a station wagon, reserving it for export to North America until September 1987. The turbocharged in-line six-cylinder had an output of 105 kW (143 hp) at 4600 rpm, which was increased to 108 kW (147 hp) in 1988. The sedan of the same model was shown in 1987 in Frankfurt/Main at the International Motor Show; in addition to the 300 D Turbo with rear-wheel drive there was now also the 300 D Turbo 4MATIC with four driven wheels. Additional air intake gills in the right fender distinguished the Turbo version from the 300 D.

A second 124-series turbodiesel was put on display in September 1988 at the Paris Motor Show. The 250 D Turbo was powered by a turbocharged 2.5-liter OM 602 engine, the one also used in the compact class. However, the unit used in the 124 series was a modified version developing 93 kW (126 hp) at 4600 rpm; the top speed was around 195 km/h (121 mph). The engine design was revised with the aim of improving the combustion process to reduce particulate emissions.

The most important means of achieving this was the use of a new prechamber featuring oblique fuel injection. This ensured more efficient combustion and also boosted output by 2.9 kW (4 hp). Together with the 250 D Turbo, the 300 D Turbo also had its three-liter engine revised. Finally, in 1989, in connection with the "Diesel '89" initiative, the non-turbocharged diesel cars also were fitted with revised engines. The improved models gave off 40 percent less particulates than their predecessors and thus met the stringent US standards even without a particulate trap.

From October 1990 onwards, as an optional extra Mercedes-Benz additionally offered an emission control system featuring an oxidation-type catalytic converter and exhaust-gas recirculation. Initially an option for conventional diesel engines, it also became available for turbodiesels at the start of 1991.

1993 - Diesel refinement in the S-Class

Diesel engines have been available for the S-Class of Mercedes-Benz since the 300 SD model from the W 116 series (1978 to 1980). The compression-ignition engine also found its way into the 126 series in the 300 SD Turbodiesel (1980 to 1985) and 350 SD Turbodiesel (1990 to 1991). What these specimens of the Stuttgart luxury class had in common is that they were sold only in North America. The story of the Mercedes-Benz 300 SD of the 140 series, which was exported exclusively to the USA and Canada from 1991 to September 1992, also begins this way.

From the fall of 1992 on, however, an S-Class car equipped with a 3.5-liter turbodiesel also could be had in Europe: the compression-ignition engine finally had arrived in the international luxury automobile segment. The car developed 110 kW (150 hp) and, with a top speed of 185 km/h (115 mph), was content with an average 9.7 liters of diesel fuel (24.2 mpg). Standard equipment included an exhaust-gas turbo-charger and an emission control system with oxidation-type catalytic converter.

1993 - New names, new models

Appropriate to its displacement, the model was renamed in June 1993, now being designated the S 350 Turbodiesel. The diesel models of the mid-sized 124 series also got new designations in 1993. They were now called E 200 Diesel, E 250 Diesel, E 250 Turbodiesel, E 300 Diesel, E 300 Turbodiesel and E 300 Turbodiesel 4MATIC.

The S 350 Turbodiesel was replaced in 1996 by the S 300 Turbodiesel. The new diesel model in the S-Class had a turbocharged engine with four-valve-per-cylinder design and intercooling; with 130 kW (177 hp) developed at 4400 rpm its output was 20 kW (27 hp) higher than its predecessor's. The engine had high torque over a very broad engine speed range; its pollutant emissions and fuel consumption were far less than the S 350 Turbodiesel's owing to optimized combustion. On top of that the top speed climbed to 206 km/h (128 mph). The S-Class with diesel engine met with increasing interest everywhere in the world: of the total 406,532 sedans from the 140 series sold, 28,101 had compression-ignition engines.

1993 - Four-valve-per-cylinder diesel and emission control as standard

In 1993 the diesel technology in several Mercedes-Benz models underwent a decisive change: as a world first, four valves per cylinder were used in the diesel. Four instead of two valves per cylinder enabled increased torque and output over an appreciably enlarged engine speed range and cut fuel consumption under full load by as much as eight percent. Owing to an improved process of combustion the particulate emissions simultaneously were reduced by about 30 percent. Initially, only the five- and six-cylinder naturally aspirated engines were converted to four-valve technology. The two-liter four-cylinder and the turbocharged engines retained their two valves per cylinder for the time being. The new engines for the C- and E-Class developed 70 kW (95 hp, 2.2-liter displacement), 83 kW (113 hp, 2.5-liter dis-placement) and 100 kW (136 hp, three-liter displacement) - and were all equipped with exhaust-gas recirculation and oxidation-type catalytic converter as standard.

1995 - Three diesels and four eyes

In 1995 the new 210 mid-series made its debut. The distinguishing external feature of the new E-Class was the front end with its four elliptical headlamps. The model range initially comprised three diesel models. The E 290 Turbodiesel, its four-stroke diesel engine featuring direct injection, exhaust-gas turbocharger with intercooler, plus emission control system with oxidation-type catalytic converter, caused quite a stir. Its in-line five-cylinder OM 602 DE 29 LA engine offered the combination of diesel technology and direct injection for the first time in a Mercedes-Benz car. Compared with the naturally aspirated three-liter engine with prechamber injection in the E 300 Diesel, which practically had the same displacement, the new design impressed observers with appreciably higher torque and lower fuel consumption. The new engine was the first step of Mercedes-Benz towards the introduction of direct-injection car diesel engines.

Diesel engines in Mercedes-Benz passenger cars: 1997 - 2006

1997 - With CDI into the future: Premiere in the C-Class

The future of diesel drive became reality at the International Motor Show in Frankfurt/Main in September 1997: in the C 220 CDI Mercedes-Benz presented a direct injection system based on a new principle, "Common Rail Direct Injection" (CDI). While conventional injection systems have to generate the pressure for each injection operation individually, the new CDI engines operate with a common pressure reservoir for all cylinders, the so-called common rail. Regardless of engine speed, this reservoir continuously maintains an optimum pressure of 1,350 bar for all cylinders; by means of solenoid valves, the ideal quantity of diesel fuel for each driving state is distributed to the injection nozzles and injected into the combustion chamber. The engine electronics individually calculate the requirements of every single cylinder dependent on the driving situation. The variable control of the injection process makes for appreciably improved mixture preparation and in effect results in lower fuel consumption and reduced pollutant emissions.

The CDI engine of Mercedes-Benz also impresses with its unusually smooth running, which can be put down mainly to so-called pilot injection. A few milliseconds before fuel injection proper, a small amount of diesel is sprayed into the cylinder, ignites, and ensures preheating of the combustion chambers. Owing to this preheating, during the main injection the pressure and temperature no longer rise so sharply, and the engine runs quieter.

The 92 kW (125 hp) four-cylinder engine of the C 220 CDI is a four-valve-per-cylinder design and develops remarkable torque of 300 Newton meters from an engine speed as low as 1800 rpm. A comparison with the predecessor model is very interesting: 30 percent more power, double the torque, ten percent less consumption. CDI thus set new standards for diesel cars and changed the image of the diesel engine for good. Now the compression-ignition engine no longer is considered just a miracle of economy, but also an agile and sporty performer.

1998 - CDI in the E-Class

New CDI diesel engines featuring common rail direct injection and turbocharger brought the new technology to the E-Class too in June 1998. The E 200 CDI got 75 kW (102 hp) out of its turbocharged two-liter four-cylinder and sprinted to a top speed of 187 km/h (116 mph). The E 220 CDI developed 92 kW (125 hp) and reached the 200 km/h (124.3 mph) mark. Yet the new models needed an average of only 6.3 liters of diesel per 100 kilometers (37.3 mpg).

The 1999 model refinement package fully established CDI technology in the E-Class: the five-cylinder of the E 270 CDI developed 125 kW (170 hp) and maximum torque of 370 Newton meters from 1600 rpm. But the most powerful diesel of the model range ran on six cylinders in the new E 320 CDI. The 145 kW (197 hp) direct-injection diesel got its maximum torque of 470 Newton meters at 1800 rpm and held it to 2600 rpm. This 3.2-liter engine took full advantage of the big torque that is the hallmark of the diesel. Compared with the previous six-cylinder diesel of the E-Class the torque increased by 42 percent. And yet the six-cylinder OM 613 DE 32 LA engine (direct injection, exhaust-gas turbocharger with intercooler, plus emission control system with oxidation-type catalytic converter) consumed on average only 7.8 liters of diesel fuel per 100 kilometers (30.1 mpg); its speed topped out at 230 km/h (143 mph).

Like the new engines, the two four-cylinder CDI units introduced in 1998 also got new turbochargers with variable turbine geometry as part of the 1998 refinement package. This increased their output by up to 14 percent: The E 200 CDI now developed 85 kW (115 hp), the E 220 CDI 105 kW (143 hp).

2000 - The strongest diesel for the S-Class

The new S-Class W 220 debuted as a diesel in 1999 in the form of the S 320 CDI. Its in-line six-cylinder delivered 145 kW (197 hp) at 4200 rpm. The torque was 470 Newton meters, obtained in a range from 1800 to 2600 rpm. The luxury sedan got up to 230 km/h with the 3.2-liter compression-ignition engine and sprinted from standstill to 100 km/h in 8.8 seconds.

By far the most powerful diesel engine in a Mercedes-Benz car made its arrival in the S-Class in the year 2000. From a displacement of four liters, the light-alloy V8 OM 628 DE 40 LA developed 184 kW (250 hp) at 4000 rpm. It delivered torque of 560 Newton meters at 1800 to 2600 rpm. A top speed of 250 km/h (155 mph) and 7.8 seconds for accelerating to 100 km/h illustrate the role of the S 400 CDI as first among the Mercedes-Benz diesel models.

2002 - The diesel returns to the coupe

Since the C 123 series of the 1970s there had been no more Mercedes-Benz coupes with diesel engines. In 2002 the CLK 270 CDI (C 209 series) was introduced. The four-stroke diesel (electronically controlled common rail direct injection, Bosch three-plunger high-pressure pump and exhaust-gas turbocharger with intercooler) was an engine that met the demands on a sporty vehicle yet operated economically. 125 kW (170 hp) at 4200 rpm were good for a top speed of 230 km/h and standstill to 100 km/h acceleration in 9.2 seconds.

New V6 engine for greater dynamism

The development of innovative features for the diesel engine continues unabated. An outstanding example from the long list of novelties is the six-cylinder V-engine which Mercedes-Benz presented in December 2004 and has been offering since the spring of 2005 in different model series where this engine replaced the previous five- and six-cylinder in-line units. The new engine made its debut in the C-Class, giving the sedan and station wagon models a highly agile character with a decidedly sporty touch. The sedan accelerates from standstill to 100 km/h in just 6.9 seconds. It is therefore not surprising that these diesel-engined cars were also made available as "Sport Edition" versions, among other things with a visual enhancement package from AMG. The "Sport Edition +" documents the dynamic nature of the modern compression-ignition engine with an even wider range of features in-cluding sports suspension.

The V6 diesel engine with direct injection develops 165 kW (224 hp) and a torque of 510 Newton meters, which is on tap from 1800 rpm and remains constant up to an engine speed of 2800 rpm. The engine complies with the EURO IV emission norm and has been featuring a particulate trap as standard equipment ever since its market launch. Weight is reduced by a crankcase made of aluminum with cast-in gray-iron cylinder liners - an absolute novelty in this displacement and performance category. As a result, the new six-cylinder weighs in at just 208 kilograms and is thus only insignificantly heavier than the previous five-cylinder engine. And the very compact dimensions of this engine with all its ancillary components allow it to be combined with four-wheel drive which, for lack of space, was not available for any six-cylinder diesel engine before.

The equally newly developed electronic control unit monitors all the engine functions - from the Instant Start System and the automatic start function through to the high-pressure pump. The VNT (Variable Nozzle Turbine) turbocharger with electrically adjustable guide blades, the exhaust-gas recirculation with control valve and the intake air throttling system are controlled to match the situation at any given point in time, on the basis of up-to-date measurements. What's more, the computer exchanges data with the seven-speed automatic trans-mission - if specified by the customer - and the Electronic Stability Program.

Premiere: The torquiest eight-cylinder diesel engine In the fall of 2005, production began of the torquiest V8 passenger-car diesel engine (OM 629), initially for the Mercedes-Benz E-Class and planned to be made available for other model series at a later stage. The 231 kW (314 hp) V8 generates its maximum torque of 730 Newton meters at an engine speed as low as 2200 rpm. As a result, the E 420 CDI accelerates from standstill to 100 km/h in just 6.1 seconds and reaches a top speed of 250 km/h (155 mph). In terms of dynamism and smooth running characteristics, this eight-cylinder represents the benchmark in its market segment. The combined fuel con-sumption is 9.3 liters per 100 kilometers (25.3 mpg). The standard specifications of the E-Class with this engine include a maintenance-free particulate trap, seven-speed automatic transmission and AIRMATIC air suspension.

Alongside the aluminum crankcase, cooled exhaust-gas recirculation and electric intake air throttling, third-generation common rail direct injection ranks among the technical tidbits of the new Mercedes-Benz eight-cylinder engine. This CDI system operates at an injection pressure raised to 1,600 bar and permits high-precision fuel apportionment - for the benefit of fuel economy and exhaust emissions.

2003 - Maintenance-free particulate trap and EURO IV norm

Mercedes-Benz made a major advance in respect of the environmental compatibility of the diesel drive in the fall of 2003. As first automobile brand in the world the company introduced diesel passenger cars built to the EURO IV norm and featuring a maintenance-free particulate trap. Mercedes-Benz offered the first traps for export to California as early as in 1985.

2005 - Particulate trap as standard in more than 30 Mercedes-Benz models

Since the early 1990s, technologies like the common rail system developed by Mercedes-Benz have reduced the fuel consumption of diesel cars by more than 25 percent. The CDI, state of the art of Mercedes-Benz diesel technology, meanwhile is represented in all the vehicle classes marketed by the brand: from the A-Class through the GL-Class to the S-Class.

More than 30 different models were affected when Mercedes-Benz in summer 2005 began fitting all diesel cars from the A- to the S-Class with diesel particulate traps as standard in Germany, Austria, the Netherlands and Switzerland. Mercedes-Benz had been offering its innovative particulate trap system, which operates maintenance-free and makes do without additives, since 2003.

Owing to economical, optimized engines, in combination with the trap, the particulate emissions are more than 90 percent less than those of earlier engines. In view of this success a retrofit solution for car particulate filters was made available from the fall of 2005, initially for vehicles of the C-Class and E-Class. Dr. Thomas Weber, member of the Board of Management of DaimlerChrysler AG, responsible for Research and Technology and Development in the Mercedes Car Group, emphasizes:

"Our retrofit solution for particulate taps is further proof of the high level of our diesel expertise and a consistent step towards environmentally compatible, fuel-saving vehicles."

Unique change of character

At the Geneva Motor Show in 2005, Mercedes-Benz not only announced the incorporation of particulate traps in the standard specifications but also reviewed over 70 years of diesel competence - the first 260 D had, after all, come off the assembly line in 1935. For decades, the diesel engine had been regarded merely as the epitome of longevity. It was known to be reliable and sound, but also somewhat sedate. In the course of time, it has lost this trait and acquired a completely new image. Today, sporty dynamism, agility, ride comfort, motoring pleasure and, not least, environmental compatibility rank among the attributes boasted by modern diesel engines. And the engineers at Mercedes-Benz have contributed to this change in no insignificant measure.

This remarkable development is verified most clearly by figures: the world's first passenger-car diesel engine in the Mercedes-Benz 260 D developed just 33 kW (45 hp), corresponding to a power-to-swept-volume ratio of 13 kW/liter (17.7 hp/liter). In the C 320 CDI, the V6 diesel engine presented in December 2004 develops an impressive output of 165 kW (224 hp) from a displacement of three liters - boasting a power-to-swept volume ratio of 55.2 kW/liter (75 hp/liter), more than four times the ratio of the 260 D.

Torque ratings - the decisive factor for tractive power from low engine speeds - rose just as dramatically, from 98 Newton meters in the 170 D of 1949 to 510 Newton meters in the C 320 CDI. In other words, some 55 Newton meters per liter of displacement in 1949 are pitted against more than three times this figure - 170 Newton meters - today.

Future development trends of the diesel engine were outlined by Mercedes-Benz at the 2005 Geneva Motor Show, among other things by means of two roadsters. In the Vision SL 400 CDI show car, a new V8 diesel engine develops 231 kW (315 hp) and transmits an enormous torque of 730 Newton meters to the crankshaft of the eight-cylinder unit.

From a displacement of three liters, the engine of the SLK 320 Triturbo develops remarkable 210 kW (286 hp) and a torque of 630 Newton meters - 70.3 kW and 211 Newton meters per liter of displacement. The triturbo engine is based on the modern V6 diesel. The show car is clad in the self-assured guise of the SLK 55 AMG. The car sprints from standstill to 100 km/h in 5.2 seconds; its top speed is limited to 250 km/h (155 mph). It combines this impressive performance with excellent fuel economy: 7.5 liters of fuel per 100 kilometers (overall NEDC consumption) or 31.3 mpg.

The economy of modern diesel engines is astounding. Whereas the world's first passenger car diesel engine in the 260 D consumed 0.3 liters of fuel on 100 kilometers to generate one kilowatt, the C 320 CDI makes ends meet with just 0.04 liters per kilowatt over the same distance, equivalent to a reduction by unbelievable 90 percent or, in other words, fuel consumption reduced by a factor of ten. This is a development which not only saves natural resources but also reduces the burden on the environment. At the same time, exhaust-gas emissions have been reduced significantly, not least by state-of-the-art filter technology. And the next step towards even greater cleanliness has already been taken - its name is BLUETEC.

Diesel engines in Mercedes-Benz commercial vehicles

1928 - Mercedes-Benz diesel tractor

Along with the six-cylinder OM 5 engine, after 1926 Mercedes-Benz developed a new one-cylinder engine which it fitted into the OE diesel tractor in 1928. The engine displaced 4.2 liters and had an output of 19 kW (26 hp) at 800 rpm.

1932 - First production light truck with a diesel engine

The Lo 2000 was the world's first light truck to be fitted with a diesel engine as standard. Daimler-Benz AG introduced it in 1932 at the Geneva Motor Show. It was powered by the new 3.8-liter prechamber diesel OM 59. This innovative vehicle design was a response of Daimler-Benz to the difficult economic situation following inflation and a world economic crisis. Customers had a high opinion of this economical and light truck.

The letters "Diesel" on the radiator next to the Mercedes star became a symbol mainly of heavy goods transport in the 1930s. Whereas the diesel engine's share of the power plants of big trucks already reached 90 percent in Germany in 1931, and trucks of five tons payload and more were fitted exclusively with diesel engines after 1934, the compression-ignition engine was much slower establishing itself in the light truck segment. The new OM 59 of 1932 was an important argument for diesel technology: the engine was less than half the size of the OM 5, but was nearly as powerful. And it gave the Lo 2000 a top speed of 65 km/h (40 mph); in 1932 this definitely sufficed to have it called an express delivery van.

1933 - Semitrailer tractors from Daimler-Benz

The semitrailer tractors built in Gaggenau from February 1933 on also profited from the success of the Lo 2000. With the LZ 4000, LZ 6000 and LZ 8000 series (four, six and eight tons) the diesel truck model range of Daimler-Benz continued to grow. In the mid 1930s Daimler-Benz built trucks with gasoline engines almost only for export.

High-speed, light diesel engines proved a key to the success of the semitrailer tractors: relatively small-volume engines with rated speeds of 2000 rpm and displacements between 3.8 liters (40 kW/55 hp) and 7.4 liters (70 kW/95 hp) powered the semitrailer tractor. In 1938 a tractor for ten tons payload was added; its six-cylinder diesel developed 74 kW (100 hp). The advantage of uncoupling tractor and semi-trailer was used by the buyers of tractors not only in the haulage sector: semitrailers were even supplied equipped as buses - this configuration went into the vernacular as "Tatzelwurm" (a mythical Alpine dragon).

1935 - 10,000th Mercedes-Benz commercial vehicle with diesel drive

Nine years after the merger of Benz & Cie. and Daimler-Motoren-Gesellschaft in 1926, the diesel engine was playing an increasingly important role in the commercial vehicle sector for Daimler-Benz AG: in Gaggenau the 10,000th commercial vehicle of the brand featuring a compression-ignition engine was delivered to a customer on April 6, 1935.

The engine range was correspondingly diversified, including engines for light and heavy-duty trucks with four and six cylinders as well as engines for urban buses.

1940 - Birth of the 300 engine series

A new era in diesel technology for commercial vehicles began at Mercedes-Benz during the Second World War: in 1940 the engineers of the Stuttgart brand took up work on an entirely new generation of diesel engines, the 300 series. The first prototype was the in-line six-cylinder OM 302, parallel to which the designers worked on the four-cylinder OM 301 unit.

Characteristics of the new engine were its compact dimensions and innovative components, for example a seven-bearing crankshaft and leaded bronze bearings with steel backings for the main and connecting rod bearings. Production commenced in 1942, but work on the 300 engine series could not be resumed until after the war.

1949 - OM 312 engine

On the basis of the OM 302, at war's end Mercedes-Benz Development resumed work on a modern commercial vehicle diesel engine. The condition was that the new unit had to be produced on machines on which Daimler-Benz manufactured a licensed version of the Opel Blitz during the latter war years and until 1949. This Mercedes-Benz L 701, as the vehicle with its wooden cab was called, the first truck of the Stuttgart brand after the war, was still powered by a gasoline engine. On the other hand, under the hood of the first post-1945 heavy-duty truck, the L 4500, was the tried and tested OM 67/4 in-line six-cylinder diesel, which developed 82 kW (112 hp) at 2250 rpm.

The diesel engine in the new L 3250 truck presented in May 1949 at the Hanover Trade Fair was now the OM 312, the first member of an extremely successful engine family. Passing through numerous stages of development, the 300 series would be the backbone of the medium-duty commercial vehicle diesel engine range from Mercedes-Benz for more than 50 years. In its first version the OM 312 in the L 3250 already developed 66 kW (90 hp) at 2800 rpm.

A 1949 brochure underscored the advantages of the new design and left no doubt as to the importance of the new truck for the commercial vehicle range of the brand: "The water-cooled, flexible six-cylinder diesel engine with an output of 90 hp and featuring controlled cylinder wall temperature and oil temperature is a particularly interesting new technical creation with its average fuel consumption of 14.4 liters per 100 km (16.3 mpg). Outstanding performance characteristics, highest operating reliability, tremendous economic efficiency, simple operation and thriftiest consumption, combined with excellent handling qualities and safe roadholding are the essential features of the new L 3250."

In the heavy-duty segment too, in 1950 a 300-series engine super-seded the diesel technology which still dated from the 1930s: the Mercedes-Benz L 6600 was powered by an OM 315 8.3-liter in-line six-cylinder, which was good for 107 kW (145 hp) at 2100 rpm.

1953 - Exhaust gas turbocharger for firefighting vehicles

The new generation also furnished a basis for technical innovations during the following years. Mercedes-Benz took an important step to boost performance by introducing the exhaust-gas turbocharger for commercial vehicle diesel engines. In a TLF 15/36 TA pump water tender, the Stuttgart company presented the first diesel engine which utilized the energy of flowing exhaust gases for charging the cylinders. The type OM 312 A engine (the A stands for Abgasturbolader = exhaust-gas turbocharger) developed 85 kW (115 hp), 18 kW (25 hp) more than the naturally aspirated basic engine.

But there had already been a few turbocharged commercial vehicle diesel engines from Mercedes-Benz before that: from 1948 the Esslingen-based Eberspächer company had been offering a suitable turbocharger as a retrofit kit for the OM 312. However, turbocharged commercial vehicle diesel engines did not gain broad acceptance until around 30 years later.

1957 - The 20,000th Unimog diesel

The new diesel engines from Mercedes-Benz not only were a success in trucks and cars. Special-purpose vehicles like the Unimog ("Universal-Motorgerät" = universal working machine) also were equipped with the diesel power unit. From the start of Unimog production to November 1957, 20,000 diesel engines were built for this powerful all-wheel-drive vehicle alone.

Originally, the diesel engines of the Unimog were identical with those of the Mercedes-Benz diesel passenger cars. In May 1963 the Unimog U 406 came out on the market with a 48 kW (65 hp) OM 312 under its hood. This was Mercedes-Benz's answer to the increasing demand for a high-powered variant of the special-purpose vehicle with the wide range of applications. The Unimog no longer saw use only in agriculture, but long since had proved its mettle in municipal service, as a firefighting vehicle, with the military and in other areas.

1963 - New model designations based on weight and output

The designations existing for the different truck models in the Mercedes-Benz range in the 1950s said nothing about the output of the engine used in each truck. The letters only indicated the basic configuration (conventional or cab-over-engine vehicle) and body. In 1963, therefore, Daimler-Benz decided to abolish the old nomenclature.

During the following months, the letter and number combinations which we know today were introduced. The last two digits stand for one tenth of the engine output in horsepower (rounded off). Before that the gross vehicle weight in tons (rounded off) is stated. Thus, the heavy-duty all-wheel-drive truck LA 2620 of 1964 has a permissible GVW of 26 tons and an output of roughly 200 hp (147 kW). Actually, the OM 346 engine developed 154 kW (210 hp) at 2200 rpm from its six cylinders with a total displacement of 10.8 liters.

1964 - Direct injection for commercial vehicle diesel engines

The OM 352 engine introduced at the 1964 Geneva Motor Show by Mercedes-Benz was the first direct-injection diesel for commercial vehicles. Direct injection results in lower consumption and higher output. Initially, however, the engines did not run as smoothly as their pre-chamber cousins. Particularly if single-hole injection nozzles were used with central combustion in a spherical combustion chamber, extremely loud noises and a high peak pressure were generated. Multi-hole injection nozzles and flat combustion chambers in the pistons were better still for fuel consumption, but likewise led to loud combustion noises and high peak pressures.

The Mercedes-Benz design engineers ultimately decided to use a four-hole injection nozzle positioned almost dead-center in the cylinder. However, it sprayed the fuel into the cylindrical combustion chamber at an angle of about 30 degrees. The fuel spray was directed at the wall of the combustion chamber; a swirl duct in the cylinder head provided for the necessary turbulence of the diesel mist in the cylinder. The ignition pressure in the direct-injection diesel rose to around 80 bar compared with 60 bar in the prechamber engine.

The operating noise of the direct-injection diesel had been sharply reduced by the time the engine was ready for production in 1964. In the car sector though, for the time being the classic prechamber diesel with its refined characteristics remained the power plant of choice for Mercedes-Benz. In the commercial vehicle sector, by contrast, the first direct-injection diesel was received very well. For buyers of trucks and buses, not only the boost in power counted. The better efficiency compared with the prechamber power plants reduced the thermal load on the engines; they proved to be particularly reliable. A pleasant side effect of the reduced load on the engine oil: the servicing intervals for oil changes were extended to 18,000 kilometers (11,200 mi.).

A four-cylinder injection engine, the OM 314, also was brought out in 1964. The first units of the new model had a displacement of 3.8 liters and developed 59 kW (80 hp) at 2800 rpm. The four-cylinder engines were used in light cab-over-engine trucks, vans, and special-purpose vehicles like the Unimog.

1968 - Turbocharging for the direct-injection diesel

A number of customers increasingly asked for a Mercedes-Benz diesel engine with fuel injection and exhaust-gas turbocharger. The turbo-charger was supposed to provide the power necessary mainly for journeys through mountain regions. For where the atmosphere gets thin, boosting the volume of air in the combustion chamber gives rise to an especially sharp increase in output.

Initially the OM 352 A was intended for use in snow cutters. Following successful road testing the turbocharged unit was also installed in trucks. The new engine premiered in the L 1413, where the turbo-charged injection engine developed 115 kW (156 hp). The use of improved turbochargers from Eberspächer, Garrett and KKK (Kühne, Kopp und Kausch) made this high-powered compression-ignition engine even more reliable.

1969 - The 100,000th commercial vehicle diesel engine

In the Mercedes-Benz Mannheim works, an anniversary was celebrated in January 1969: the 100,000th diesel engine for commercial vehicles built in the plant on the River Neckar came off the assembly line.

1969 - Hybrid research on diesel-engined buses

Mercedes-Benz displayed the first prototype of the OE 302 hybrid electric bus at the 1969 International Motor Show in Frankfurt/Main. The aim of optimizing the propulsion system of line-service buses in this project was mainly to reduce their emissions in downtown areas: battery current served to power the buses in the sensitive zones of city centers; on highways and in less densely populated city districts the serial hybrid drive changed to the diesel engine. In the serial hybrid system, however, the compression-ignition engine did not act directly upon the wheels, but supplied the electric traction motor with energy via a generator.

The successor to the OE 302 was presented in 1978 at the "transport 78" trade show in Munich: the OE 305 hybrid electric bus again had an electric traction motor which a diesel engine powered via the generator. The heavy batteries notwithstanding, the capacity of the drive system was designed so that the bus attained the performance of a comparable diesel-powered O 305 urban bus. Despite the high load on them, the storage batteries survived an average of 800 recharging operations. In the course of 1979 a total of twenty OE 305 hybrid electric buses took up local public transport service in the cities of Stuttgart and Wesel. By 1983 the vehicles had covered more than 1.3 million kilometers (800,000 mi.).

In 1979 Daimler-Benz also introduced a second hybrid bus: besides the standard diesel engine, the Duo Bus or dual-powered bus was equipped with an electric motor which was supplied with current by an overhead cable. Whereas the electric motor was used in the city, in the country the bus operated on its diesel drive. Before the end of 1979, three of the vehicles commenced trial operation in regular service in Esslingen. During the next few years more than 50 of these vehicles would be used internationally in regular service.

These test vehicles of the 1970s presage the part that the diesel drive would play in advanced hybrid concepts for passenger cars after the year 2000. Other bus concepts with innovative drive systems were the diesel-electric O 405 GTD dual-powered bus (1986) and the diesel-electric O 405 GNTD bus (1994). This low-floor articulated bus had a diesel engine that powered a generator that supplied electric energy for the wheel hub motors.

1970 - New OM 400 engine series

A new engine series for heavy-duty trucks came out on the market in 1970. The 400 family of Mercedes-Benz diesel engines made its debut in the new LP 1632 as a V10 engine with a displacement of 16 liters and an output of 235 kW (320 hp) at 2500 rpm. The new units were the designers' response to a proposed law intended to speed up over-the-road freight transport: in 1968 the German Federal Minister of Transport, Georg Leber, introduced a bill stipulating that from 1972 on new vehicles must have an engine output of six kW (eight hp) per ton of gross combination weight.

Medium-duty and light trucks, which are more likely to be used in short-radius distribution work and pull trailers less frequently than their heavyweight brothers, were not so much affected by this regulation. But for long-distance trucks and tractors and other heavy-duty commercial vehicles, the output of the 300-series engines was no longer adequate under the conditions set by the new laws. From 1969 Mercedes-Benz thus set about developing the new engine generation.

The veil was lifted on the OM 403 with diesel direction injection in 1970. Together with the engine, the LP 1632 truck presented another innovation - a tilt cab. This appreciably simplified the servicing of the engine in a COE truck and invalidated a major argument in favor of conventional trucks. In 1972 the bigger engine was complemented by the OM 402 V8 diesel, with 12.8 liters displacement and 188 kW (256 hp) output at 2500 rpm. For medium-duty trucks, the OM 401, a V6 diesel with 9.6 liters displacement and 141 kW (192 hp) at 2500 rpm, followed in 1975.

1970 - Assembly of commercial vehicle diesel engines in Iran

Iranian Diesel Engine Manufacturing Company (IDEM) in Tabriz, Iran, began assembling diesel power units for commercial vehicles in 1970. Daimler-Benz had owned a stake in the company since 1969. Engines of the 300 family were built there: around 180,000 units of the OM 314, OM 352 and OM 352 A engines were produced in the first 30 years of this cooperation.

The commercial vehicle diesels from Mercedes-Benz conquered the world during this decade: in 1979 Mercedes-Benz awarded licenses for the 300 and 400 series to Industrial Development Company of South Africa (IDC). Diesel engines of Stuttgart origin were built and adapted to various vehicles and pieces of equipment in the engine plant of Atlantis Diesel Engine (ADE) north of Cape Town.

1975 - The one-millionth commercial vehicle diesel engine from the Mannheim plant

In Germany, too, the manufacture of commercial vehicle diesels was running at full swing. In 1975 a V6 diesel from the OM 401 series became the one-millionth commercial vehicle diesel engine to be built at the Mercedes-Benz plant in Mannheim. The 141 kW (192 hp) engine was donated to the city of Mannheim, which installed it in a Mercedes-Benz fire truck.

1980 - Turbocharged and intercooled OM 422 LA

As early as the mid-1970s Mercedes-Benz began developing commercial vehicle engines which featured an intercooler in addition to the exhaust-gas turbocharger. Cooling reduces the temperature of the air compressed by the turbocharger, thus increasing the oxygen content. This permits obtaining higher power in engines with the same technical data: the OM 422 A V8 diesel developed 243 kW (330 hp) with 14.6 liters displacement, whereas its intercooler-equipped brother introduced in 1980 developed an output of 276 kW (375 hp).

This OM 422 LA engine was the first commercial vehicle engine from Mercedes-Benz to have an intercooler. It was followed in 1982 by a 300 series engine, the OM 362 LA, with the same technology and an output of 141 kW (192 hp) at 2600 rpm. 300 series engines like this were built in large numbers mainly for export.

1987 - The 500,000th engine of the OM 400 series

Within 17 years, 500,000 engines of the OM 400 series were built. The anniversary engine originated in Mannheim in January 1987. From the original OM 403 V10 engine, meanwhile, various V6 and V8 drive units had emerged whose power output in production trucks ranged from 140 to 320 kW (190 to 435 hp). A special heavy-duty hauling variant of the V10 engine even boasted 368 kW (500 hp).

1996 - Debut of new engine families 500 and 900

Together with the new Actros heavy-duty truck, in 1996 Mercedes-Benz introduced a new, innovative engine family. The diesel power plants of the 500 series made their debut with a V6 engine, the OM 501 LA (230 kW/313 hp - 315 kW/428 hp) and a V8 engine, the OM 502 LA (350 kW/476 hp - 420 kW/571 hp). Equipped with exhaust-gas turbocharger and intercooler, the engines featured individual unit pumps and attained their maximum torque at 1080 rpm. While the V6 had one turbocharger for the entire engine, the V8 was distinguished by one turbocharger for each of the two cylinder banks.

Together with the 500 series Mercedes-Benz introduced the new 900 series of in-line diesel engines for the new Atego truck family, compris-ing mainly light and medium-duty vehicles. The four-cylinder OM 904 LA developed between 90 kW and 125 kW (122 hp and 170 hp), the six-cylinder OM 906 LA delivered 170 kW or 205 kW (231 hp or 279 hp).

With the two new engine families, plus the 457 series borrowed from South American production in 2001 for the new Axor family, Mercedes-Benz soon covered the entire commercial vehicle spectrum with different ultramodern diesel power units. The engines are perfectly matched to the other components of the drive system. An individual drivetrain can thus be put together from different modules. This results in an extraordinary variety of models and specification options.

1998 - Diesel-electric drive system in the Cito midibus

In 1998 Mercedes-Benz introduced the Cito urban midibus. The innovative low-floor vehicle had a diesel-electric drive system. An OM 904 LA diesel engine with an output of 130 kW (177 hp) served to drive a generator. The generated electric power was fed into the electric traction motor. Thanks to this drive technology, the Cito excelled with smooth and continuous acceleration. This driving characteristic cannot be obtained with a purely mechanical drivetrain.

The unit consisting of diesel engine, generator and electric motor was installed in the rear of the vehicle and called a power pack. Mercedes-Benz developed the system together with Siemens. The Cito was built from 1999 to 2003. In 2000 it won the distinction of "Bus of the Year 2001."

2003 - More torque for the OM 500 series

All variants of the OM 500 were revised in 2003. The V6 and V8 engines of the Actros got slightly higher power ratings. But most of all the torque of most of these diesel engines was markedly increased. The engines' ease of servicing also was improved with wear-free materials and extended servicing intervals of as much as 150,000 kilometers (93,200 mi.) in long-haul operation.

2004 - 450 kW (612 hp) in the Actros Black Edition

This special edition of the Actros, limited to 250 units, is equipped with the OM 502 LA engine, which develops 450 kW (612 hp) at 1800 rpm from a displacement of 16 liters, making this the first Mercedes production truck to clear the 600-hp hurdle.

2006 - The 500,000th reconditioned commercial vehicle engine

A V8 diesel of the 500 family became the 500,000th reconditioned diesel engine for Mercedes-Benz commercial vehicles in 2006, coming off the assembly line at the Mannheim plant. Genuine reconditioned engines or factory-reconditioned components from Mercedes-Benz are the ideal solution for providing commercial vehicles with a virtually new drive system. Reconditioned engines are typically used for trucks and buses which run up high mileages in a short time - the so-called mileage millionaires. But also for vehicles with expensive special bodies and correspondingly high residual value, the replacing of the engine suggests itself when the original unit shows weaknesses.

In a reconditioned engine, not only all defective and worn-out parts are replaced, but all design changes, innovations and improvements made since original manufacture are incorporated into the unit. With that, the reconditioned component gets an entirely new identity, recognizable by the reconditioned-unit model plate. And Mercedes-Benz gives the same warranty on it as for a brand-new component.

Reconditioned engines are available for the 500, 900, 457, 300 and 400 series. The V-engines of the heavy-duty 500 series are the heart of the Actros and are also premium engines operating in high-quality touring coaches like the Travego. The 900 series powers the Atego, Vario, Cito, Citaro and Unimog vehicles; the 457 family operates in the Axor and Citaro.

But even for the older series, the 300 and 400, production of which was discontinued, there are still replacements available. For the most part, these engines are reconditioned using original production equipment. They are available then, for example, to the fans of vintage Unimogs.

Engine reconditioning has a long tradition in Mannheim: since 1949 the factory has been dismantling commercial vehicle engines, completely overhauling them and returning them as good as new to customers. The 200 employees in engine reconditioning overhaul some 5,000 units annually. This requires detailed knowledge: there are more than 2,700 different engine variants on the list.

BLUETEC - The future of the compression-ignition engine

2005 - BLUETEC for commercial vehicles

In both cars and commercial vehicles, Mercedes-Benz has continuously advanced diesel technology. Standards for the reduction of the pollutants in diesel exhaust gas were set in 2005 in the commercial vehicle segment when Mercedes-Benz introduced the BLUETEC technology for minimizing emissions in Europe. Since then this process has been very successfully applied in Mercedes-Benz commercial vehicles: in February 2006 the 10,000th BLUETEC truck with EURO V engine was delivered to a customer.

BLUETEC is used in the commercial vehicle segment with an SCR (Selective Catalytic Reduction) catalytic converter and AdBlue injection. An aqueous urea solution is sprayed into the exhaust flow and together with the catalytic converter reduces nitrogen oxides (NOx) by around 80 percent. This is the most effective method in existence for reducing nitrogen oxides in diesel engines. In 2005 trucks and buses with BLUETEC already met the particularly stringent EURO IV and EURO V emission standards that will apply to the production of all engines beginning in the fall of 2006 and 2009, respectively.

Tried and tested diesel engines as the basis

The basis of the first revolutionarily clean BLUETEC diesels are the tried and tested 500- and 900-series engines. In the Actros the V6 power plant OM 501 LA in its weakest version develops 235 kW (320 hp) at 1800 rpm. The engine achieves its maximum torque of 1,650 Newton meters at 1080 rpm. In addition to turbocharger and intercooler, the engine has a central, high-set camshaft, fully electronic engine management with single-cylinder injection pumps, and centrally arranged eight-hole nozzles providing an injection pressure of up to 1,800 bar.

The most powerful unit of the 500 series is the OM 502 LA with 16 liters displacement, an output of 440 kW (598 hp) at 1800 rpm and torque of 2,800 Newton meters at 1080 rpm. Injection is based on the same principle as in the V6 unit, except that seven-hole nozzles are used. Both V-engines have a four-valve-per-cylinder design. Whereas in the V6 version the rated outputs remain largely the same and a new top V6 variant with 350 kW (476 hp) and maximum torque of 2,300 Newton meters has been added, BLUETEC generally gives the existing V8 engines a higher output. The most powerful OM 502 LA now develops 440 kW (598 hp) at 1800 rpm and has maximum torque of 2,800 Newton meters.

The 900-series engines with BLUETEC likewise cover the entire range of variants previously offered as EURO III engines. The OM 904 LA in the basic version as water-cooled in-line four-cylinder with three valves per cylinder develops 95 kW (129 hp) at 2200 rpm. The engine fea-tures a turbocharger, intercooler and fully electronic engine manage-ment with nine-hole injection nozzles which achieve injection pres-sures of up to 2,000 bar. The maximum torque of 500 Newton meters is available at 1200 to 1600 rpm.

The most powerful BLUETEC engine of the Atego is the OM 906 LA, a water-cooled in-line six-cylinder with three valves per cylinder. The technical details are similar to those of the four-cylinder unit; however, this engine gets 210 kW (286 hp) at 2200 rpm with 6.4 liters displacement. This is good for torque of 1,120 Newton meters at 1200 to 1600 rpm.

The OM 457 LA and the OM 906 LA in the Axor also give a good account of themselves as environment-friendly BLUETEC engines. The water-cooled in-line six-cylinders in four-valve-per-cylinder design work with a turbocharger and intercooler, a central, high-set camshaft, fully electronic engine management with single-cylinder injection pumps, and centrally arranged seven-hole or nine-hole nozzles providing an injection pressure of up to 2,000 bar. In its basic version the EURO IV OM 906 LA develops 188 kW (256 hp) at 2200 rpm. The engine attains its torque of 970 Newton meters at 1200 to 1600 rpm. The most powerful version of the EURO V OM 457 LA engine with its twelve li-ters displacement develops 315 kW (428 hp) at 1800 rpm, and the torque of 2,100 Newton meters is available at 1100 rpm.

BLUETEC in passenger cars

The clean Mercedes-Benz BLUETEC commercial vehicles are trendsetters for the car sector, as the highly innovative system for reducing nitrogen oxides and other emissions also lends itself to application in passenger cars: BLUETEC reduces nitrogen oxides to such an extent that the toughest emission limits worldwide can be met. An advanced concept car with a forward-looking hybrid drive, in the shape of the S 320 BLUETEC HYBRID, was already shown by Mercedes-Benz at the Frankfurt International Motor Show in 2005. With an electric motor integrated in the powertrain, the concept car is a "mild hybrid", with significantly reduced fuel consumption especially in inner-city stop-and-go traffic. The diesel engine switches itself off whenever it is not required. All the modifications and features combined reduce the fuel consumption of the BLUETEC HYBRID by some 20 percent versus the comparable predecessor model. The combined output of this S-Class car is 243 hp (179 kW); the combined torque is as high as 575 Newton meters. The car accelerates from standstill to 100 km/h in 7.2 seconds, and its top sped is electronically limited to 250 km/h (155 mph). Fuel consumption (New European Driving Cycle) is as low as 7.7 liters per 100 kilometers (30.5 mpg).

In early 2006 the Stuttgart people then presented BLUETEC for passenger cars as a ready-for-production package consisting of several components. The extensive optimization of the engines and the combustion processes taking place inside them constitutes the basis of this package. With solutions like multi-hole injection nozzles, the use of the latest generation of CDI technology and other measures, the raw emissions are cut to an extremely low level. This is where the emission control system with an oxidation-type catalytic converter (for hydrocarbons and carbon monoxide) and a particulate trap comes in. The final stage is nitrogen oxide reduction by the BLUETEC component proper.

2006 - E 320 BLUETEC, the future of the diesel car

It's the world's cleanest diesel: in October 2006 the E 320 BLUETEC hits the US market as the first production BLUETEC car; the market launch of BLUETEC cars in Europe is scheduled for 2008. The E 320 BLUETEC is an innovative model which is based on the sophisticated 320 CDI V6 and relies on the BLUETEC technology developed by Mercedes-Benz. BLUETEC is the designation for a highly efficient method of minimizing nitrogen oxide emissions already used in commercial vehicles. In contrast to commercial vehicles, the E 320 CDI BLUETEC does not make use of AdBlue injection but reduces nitrogen oxides with a system based on an improved storage-type catalytic converter.

The question may occur why the E 320 BLUETEC makes its debut in the USA. One reason, of course, is the growing demand for economical and at the same time clean cars in that country, caused by rising fuel prices. But there's yet another reason for this specific timing: "The introduction of clean diesel fuel in the USA is something we have been fighting for alongside others for a long time, and an opportunity we wish to use from Day One," said Thomas Weber, head of Corporate Research at DaimlerChrysler and of Development within the Mercedes Car Group, when the car was introduced in Las Vegas, Nevada. Modern diesel-engined cars which, in West Europe, account for more than half of new registrations annually, were unable to develop their full potential in the USA due to the excessively high sulfur content in the fuel until now. This changes at the end of 2006 thanks to the nation-wide introduction of clean diesel fuel with a sulfur content of just 15 ppm. The so-called Ultra Low Sulfur Diesel (ULSD) will be available at up to 76,000 gas stations in the USA in a first step and thereby permit the use of BLUETEC. With this innovative diesel technology, Mercedes-Benz is also able to remain below the strictest globally applicable limits where nitrogen oxide emissions are concerned. Hence, all the preconditions for the breakthrough of modern diesel technology in the USA are fulfilled.

Storage-type catalytic converter or AdBlue injection

The diesel principle has come a long way from Rudolf Diesel's invention to the modular BLUETEC system. Time and again DaimlerChrysler contributed decisive innovations to develop the diesel drive to its present level. Thus, 70 years since its premiere in the Mercedes-Benz 260 D, the compression-ignition engine presents itself today as a high-performing and economical high-tech drive with the potential for meeting even the toughest international emission limits in the future.

Mercedes-Benz demonstrated the direction in which developments in the passenger car sector are going with the E 320 BLUETEC and with concept vehicles in 2006, first and foremost the Vision GL 320 BLUETEC, the Vision CLS 320 BLUETEC and the Jeep® Grand Cherokee BLUETEC concept car. GL and Jeep® have an SCR catalytic converter with AdBlue injection; the CLS, like the E-Class, features an improved nitrogen-oxide storage-type catalytic converter. In addition, as early as 2005, at the International Motor Show in Frankfurt/Main, the S 320 BLUETEC based on the new S-Class was put on display.

BLUETEC's tremendous potential in the SUV is impressively illustrated by the GL-Class study. The car is fitted with a V6 diesel engine which yields an output of 155 kW (211 hp) and torque of 540 Newton meters. Thanks to BLUETEC the concept car combines convincing performance with great fuel economy and the lowest emissions: the expected consumption of 9.4 liters of diesel fuel per 100 kilometers (25 mpg) will be 20 to 40 percent less than that of comparable gasoline-engined SUVs, and the car will comply even with the harshest emission laws.

Eight cylinder power for the S-Class

In December 2006, Mercedes-Benz adds another Diesel variant to the S-Class range (W 221), the S 420 CDI. The eight-cylinder car has a modern V8 CDI engine with a displacement of four liters which delivers 320 PS (235 kW) and a torque of 730 Newton meter. For efficient and smooth power transmission, the 7G-TRONIC is installed. Fuel consumption (New European Driving Cycle) is as low as 9.4 to 9.6 liters per 100 kilometers and thus under the magical ten liter line.

Evolution of the compression-ignition engine in the car

Mercedes-Benz built the first diesel passenger car in 1936. 1971 saw the one-millionth car with compression-ignition engine since the Second World War roll off the assembly line. And in 1976 the C 111-II with diesel engine set standards on its record-breaking run in Nardo. The history of diesel technology is punctuated again and again by great innovations - especially owing to the initiatives of Mercedes-Benz. Since about 1990 the pace of technological development has picked up very strongly. BLUETEC represents the latest stage of this diesel evolution.

Where the development of the compression-ignition engine into a clean and powerful drive for future automobiles can take us is shown by studies like the S-Class BLUETEC Hybrid which combines the low-emission diesel with an electric motor. At Mercedes-Benz the diesel has great potential as a high-tech drive of the future.

Retracing history: Long-distance trip from Paris to Beijing

13,600 kilometers in 26 days, powered by diesel engines. From Europe to Asia through nine countries. Not in the shortest possible time but with the greatest possible fuel economy: this is the brief for the "E-Class Experience Paris - Beijing". The long-distance trip is far from being just another competition; it is both a demonstration of modern diesel technology and a trip in recognition of an early master-stroke in motor sport.

On October 21, 2006, a fleet of 36 Mercedes-Benz E 320 CDI set out from Paris on a modern-day automotive adventure, and the cars are expected to arrive in Beijing on November 17, with about 500,000 kilometers on the clock and the experience of having covered a unique route between two major world cities. But why travel from Paris to Beijing? The answer is provided by the French "Le Matin" newspaper of January 31, 1907: "Is there anybody who would like to travel from Paris to Beijing in an automobile this summer?" the newspaper asked its readers.

Mind you, this appeal dates back to the beginning of the 20th century - to a time when automobiles were high-legged contraptions with open bodywork. An engine output of ten horsepower was considered luxurious, and 40 hp was seen as gigantic power potential. The automobile - in the form of the three-wheeled Patent Motor Car - had been invented by Karl Benz just 21 years earlier. Only 13 years earlier, the first car race had been staged between Paris and Rouen - of the 21 competitors, just 15 had reached the finish, among them nine cars with Panhard-Levassor engines built under a Daimler license and one three-hp Benz "Vis-à-vis".

And now, in 1907, one hundred times the distance was to be covered from Paris to Beijing? This was indeed the brief - and "Le Matin" did find drivers who were determined to prove the technical superiority of the automobile over the horse over this distance. However, following the initial euphoria with numerous registrations, just eleven daredevils in five cars remained in the end. They set out from Beijing on June 10, 1907, because the route had to be tackled in the opposite direction on account of weather conditions.

The convoy set out fully laden with provisions, replacement parts, tools and equipment for any salvage operations required - the route did after all lead for a major part through rough territory without any proper roads. From today's point of view, the conditions for man and machine were unimaginable: railway tracks were used as bumpy trails; ox-drawn carts pulled the early automobiles along swampy paths and over steep mountain passes where the engines' power did not suffice. Road structures proved to be less than suitable for motor vehicles, too: quite a few ramshackle bridges simply collapsed after having been crossed by the convoy.

Under these conditions, technical defects on the cars were the lesser evil even if they forced the competitors to give up. The convoy made headway only very slowly. After 62 days, finally, a 40-hp Itala with Prince Scipione Borghese at the wheel arrived in Paris, welcomed by the Triumphal March from the opera "Aida". The three cars which had remained in the race arrived three weeks later, but their teams were welcomed just as enthusiastically as Borghese in his Itala. On the strenuous trip from China to France, the automobile had proved its capabilities and performance once and for all.

<"The E-Class Experience Paris - Beijing" retracing this long-distance trip sets out 99 years later, and again, the undertaking meets with overwhelming interest. Some 50,000 online registrations were received for the driver teams selected by Mercedes-Benz for some of the E-Class cars. From this large number of interested parties, 360 persons from 35 countries emerged as lucky winners. They are now driving sections of the route with different lengths on the way from France to China.

Dieter Zetsche personally saw the convoy off in Paris. The chairman of the Board of Management of DaimlerChrysler not only wished the participants well but also sounded a note of caution, saying that although the trip would not be as dangerous as the original in 1907, participants were still in for a modern adventure. For each leg, the start and finish are specified but participants are free to select the route in-between and left to their own devices on the journey.

The E 320 CDI cars are all individually decorated with adhesive national flags. Some of the cars are equipped with 4MATIC four-wheel drive. Three of the 36 cars have BLUETEC technology - the cleanest diesel in the world. One car even comes from the GUARD series to test the armoring over such a long distance. The armored car carries a valuable load, namely three magnum bottles of champagne - to be opened at the finish. The most unusual cars are two taxi cabs from Paris and Stuttgart, which accompany the convoy over the entire distance - with taximeter running. The fare in the German taxi comes to 16,050 Euros at the end of the fourth leg after just 12,000 kilometers. The trip in the Parisian taxi would have been clearly more expensive: At that point, the meter already displays the proud amount of 34,090 Euros. Upon arrival in Beijing, the total reaches nearly 40,000 Euros.

The unique long-distance trip from Europe to Asia leads through France, Germany, Poland, Lithuania, Latvia, Estonia, Russia and Kazakhstan to China. It is quite a challenge, not just because of the low temperatures, the black ice, snow and short daylight periods to be expected. Daily legs of up to 750 kilometers through almost impassable terrain, under unaccustomed traffic conditions and across mountain passes up to 2,900 meters high call for all-out concentration, great experience and perfect fitness on the part of the drivers who take turns at the wheel on five legs. These include international journalists, VIPs and online applicants. Including the support vehicles, the fleet for the "E-Class Experience" comprises some 60 vehicles including a team of doctors. Michelin takes part with a workshop vehicle to supply the teams with tires. During the entire trip, Aral provides the required sulfur-free diesel fuel with a cetane rating of 55, which is not yet available at the filling stations in each country along the route. In all, some 10,000 liters of diesel fuel are needed.

The route from Europe to Asia is subdivided into five major legs. The one from Paris to St. Petersburg is 3,550 kilometers long and comes under the heading of "Old World Splendor". The participants pass through the most scenic cities and places of Old Europe, as well as through largely unspoiled areas such the lake district of Masuria in the north-east of Poland. From St. Petersburg to Yekaterinburg, the 2,700-kilometer route leads through the "Unknown Part of Europe", largely in the tracks of the 1907 trip. The leg from Yekaterinburg leads "From Europe to Asia". On this leg, the convoy leaves the original route and drives through Kazakhstan to the former capital of Almaty, where another 2,490 kilometers are completed. The participants then have to cover another 3,100 kilometers through "China's Wild West" before they arrive in Lanzhou in China. There, they join the Silk Road and en-counter the western parts of the Great Wall of China. The last leg to Beijing, simply and meaningfully named "Chinese Landmarks", leads through the valley of the Yellow River, the Gobi Desert and the pastures of Central Mongolia, adding another 1,740 kilometers to the clock.

The cars correspond to the production versions but have been specially prepared for the trip. They all feature the suspension for tropical conditions, which is optionally available to all customers and raises ground clearance by five centimeters. The onboard equipment also includes state-of-the-art communications and navigation systems to ensure that the teams find their way but can also be located and contacted at any time. A road book is made available, providing a rough outline of the route, but the teams are free to select their individual routes to the day's finish. Nevertheless, the schedule leaves hardly any time for detours, especially since the observance of the speed limit is monitored. It is, after all, not a question of completing the journey as quickly as possible but of achieving the greatest possible fuel economy over the entire distance.

The cars arrive in the Chinese capital on November 17 - an international convoy in historical footsteps and boasting state-of-the-art technology. The aim is to arrive in time for the opening of "Auto China", the most important national motor show in China. The best average fuel consumption is 7.19 liter per 100 kilometer. The overall average consumption of all 36 cars is 8.32 liter. "During this endurance test of a total of more than 500,000 kilometres, the 33 E 320 CDI and three E 320 BLUETEC impressively showed the potential of our high-tech diesels. They proved that driving enjoyment, great fuel economy and environmental compatibility are not mutually exclusive," says Dr. Dieter Zetsche when the cars arrived at Beijing's historic Yongding Gate, the southern access point to the "Holy Axis" of the Forbidden City. The participants then have the opportunity to pop the corks because Mercedes-Benz has once again provided proof of the outstanding performance of its modern diesel-engined cars in terms of emissions, fuel economy and range - an all-out success achieved despite extremely difficult conditions.

Diesel in motor sport, research and record-breaking cars

1923 - Truck test trip from Stuttgart to Berlin and back

The new truck of Daimler-Motoren-Gesellschaft (DMG) needs ten days for its test drive in September 1923. The commercial vehicle with the new air-injection diesel engine (29 kW/40 hp at 1000 rpm) demonstrates its practical usefulness on a journey from Berlin to Stuttgart and back. The trip between the DMG factories lasts from September 20 to 30, 1923.

1954 - Test drive through the USA

Bill Carroll undertakes a test drive straight across the USA in 1954 in a Mercedes-Benz 190 D. The journey of 8,243 kilometers (5,122 mi.) takes the motor sport journalist from Seattle to New York. The diesel fuel for the ride across the continent costs the tester all of 32 dollars and 27 cents. "For Americans this fuel consumption is utterly sensational," a German report on the journey says. And the journalist's conclusion is an unequivocal recommendation to buy: "For anyone who has to drive long distances, the Mercedes-Benz 190 D is the best car."

Mercedes-Benz bets on the publicity value of the test drive from Pacific to Atlantic. Rightly so: "The huge interest in this achievement of Bill Carroll and the general admiration for it permit us to assume, without exaggeration, that Mercedes-Benz diesel passenger cars will now continue their triumphal march through the United States." Such is the resume of a report of the Stuttgart company on the American diesel marathon.

1955 - Triple victory in the Mille Miglia

The 180 D writes racing history too: in 1955, at the Mille Miglia, Mercedes-Benz dominates not only in the overall rankings, with Stirling Moss/Denis Jenkinson and Juan Manuel Fangio in the 300 SLR scoring a double victory. Stuttgart is also successful in the diesel ranking: Helmut Retter and Wolfgang Larcher win their class in a Mercedes-Benz 180 D. Their average speed is 94.6 km/h (58.8 mph). Karl Reinhardt and Wulf Wisnewski come in second, followed by Arturo Masera and Pasquale Cardinali. In the general classification the three 180 D's take the places 201, 214 and 220. This outstanding victory in their class impressively demonstrates the capabilities of the diesel drive of the Stuttgart-built sedans.

1959 - Victory in the Africa Rally

In 1959 Mercedes-Benz racing driver Karl Kling again shows that the diesel drive can deliver a good sporting performance: with Rainer Günzler as navigator, he wins the Africa Rally over 14,045 kilometers (8,728 mi.) from Algiers to Cape Town in a 190 D. His average speed: 80.6 km/h (50.1 mph). Former Grand Prix driver Kling has succeeded the legendary Alfred Neubauer as racing manager at Mercedes-Benz - a position he holds from 1956 until 1968.

1959 - Diesel record in the 190 SL

A private rally team sets a world record for diesels in 1959 in a Mercedes-Benz 190 SL. The small roadster is specially fitted with a revised OM 621 engine. The four-cylinder unit displaces two liters and has an output of 44 kW (60 hp). That suffices to set a 24-hour record averaging a speed of 124.1 km/h (77.1 mph) in a 190 SL which, apart from the engine, is a stock car.

In 1961 the private rally enthusiasts repeat their attempt. This time the two-seater is thoroughly prepared to undertake the record run: all trim has been removed, and there is only a small, semicircular pane as windshield. With a 48 kW (65 hp) diesel engine under the hood, this time the record-breaking car averages 142.3 km/h (88.4 mph) over five kilometers (3.1 mi.) from a flying start.

1972 - Across the USA in a 220 D

11,000 kilometers (6,835 mi.) from New York through the United States in a Mercedes-Benz diesel - the customer magazine "Mercedes-Benz in aller Welt" describes this journey in 1972. The red sedan drives through big cities and across prairies, mountains and deserts on its way from coast to coast. The 220 D proves a reliable vehicle; on the Bonneville Flats in Utah it even dashes to 140 km/h for the travel diary.

1975 - Dieselstar

A Mercedes-Benz five-cylinder diesel engine with turbocharger powers the "Dieselstar" experimental car of motor journalist Fritz B. Busch in 1975. Busch built the record-breaking vehicle on the basis of a Formula 2 racing car. On November 16, 1975, on the test track in Ehra-Lessien (Lüneburg Heath) it establishes a world record for diesel cars, attaining a top speed of 253.7 km/h (157.6 mph). This is all the more remarkable in view of the fact that the existing diesel records have been established on straight-ahead stretches of the salt flats in Utah, USA. Busch, by contrast, also has to negotiate bends and brake the car on the test track.

The Mercedes-Benz engine for the record attempt is fitted with an AiResearch turbocharger and a special Bosch injection pump and is slightly modified: smaller cylinder bores reduce the displacement to 2,999 cubic centimeters; to handle the high loads the unit is also provided with a nitrided crankshaft, a heavy-duty oil pump and special injection nozzles. All said and done, the engine develops 138 kW (187 hp) at 4500 rpm.

1976 - C 111-II D

A year later, Mercedes-Benz themselves set as many as three world records for diesel cars: based on the C 111 concept car, a diesel racer takes shape which is used on record-breaking runs in Nardo, Italy. Among other things Stuttgart secures itself the best times for 5,000 miles (average speed 252.540 km/h or 156.9 mph), 10,000 kilometers (252.249 km/h or 156.75 mph) and 10,000 miles (251.798 km/h or 156.47 mph). In all, the C 111-II D posts 16 world records - 13 for diesel cars only, and three absolute record times. The C 111 actually originated as a test car for the rotary piston engine. But the end of the Wankel project after the second stage of development put this beautiful 1969 coupe on ice for the time being. Now the three-liter compression-ignition engine from the 240 D 3.0 gives the breathtaking sports car a new lease on life. The power unit gets the racer running with 140 kW (190 hp).

1978 - C 111-III<7b>

Two years later a new version of the C 111 with diesel engine again takes aim at a world record. This time, the record-breaking coupe is much changed from the original design: narrower, with a longer wheelbase, full fairings and extremely sophisticated aerodynamics, including fintails. The three-liter diesel engine now develops 169 kW (230 hp) thanks to a turbocharger and intercooler; the torque of the diesel racer has been boosted to 402 Newton meters. On April 30, 1978, the car maintains an average speed of 315 km/h (195.74 mph) on the twelve-kilometer circuit at Nardo for over twelve hours. Its consumption is only about 16 liters of diesel fuel per 100 kilometers (14.7 mpg). That in itself should have earned it a world record. This time the C 111-III establishes nine absolute speed records, irrespective of engine type and displacement.

1992 - Biodiesel test with Mercedes-Benz taxis

The diesel engine also plays an important role in the application of alternative fuels. As early as 1992, Mercedes-Benz takes part in a large-scale test in Freiburg in which diesel taxis run on rapeseed oil methyl ester instead of diesel for one whole year.

2003 - F 500 Mind research car

At the 2003 Tokyo Motor Show, Mercedes-Benz presents a diesel hybrid drive in the new F 500 Mind research car. The engineers combine the high-torque V8 diesel engine of the Mercedes-Benz S-Class with an electric motor arranged between the internal combustion engine and the modified automatic transmission. Pairing the two produces the most powerful, torquiest hybrid drive for rear-wheel-drive cars in 2003. While the V8 diesel develops 184 kW (250 hp) and attains a maximum torque of 560 Newton meters, the electric motor contributes an additional 50 kW and 300 Newton meters maximum torque. The classic division of labor between the two drive systems, depending on the situation, and the recuperation of energy from braking allow the diesel hybrid drive to reduce fuel consumption in the European driving cycle by about 20 percent versus a comparable production vehicle.

2003 - Synthetic diesel fuel

In 2003 Mercedes-Benz presents an alternative diesel fuel. It is obtained synthetically from vegetable matter, which makes this fuel neutral with respect to carbon dioxide. The CO2 blown out the tailpipe during combustion equals exactly the amount which the plants extracted from the atmosphere during the growth process.

2004 - GST 2 concept car

The Vision GST 2 displayed at the North American International Auto Show in Detroit in January 2004 has a diesel hybrid drive. The Grand Sports Tourer concept car is thus more than a successor to the gasoline-engined Vision GST of 2002. The pioneering hybrid consisting of a V8 diesel and an electric motor is similar to the one already used in the F 500 Mind. But now the hybrid operates in a vehicle with four-wheel drive and six-speed automatic transmission. The Vision GST 2 with diesel hybrid affords ample dynamism and driving pleasure. The two power units with their total output of 300 kW propel the concept car from standstill to 100 km/h in 6.6 seconds; the top speed is elec-tronically limited to 250 km/h (155 mph).

2005 - S-Class Hybrid

In Detroit in 2005 Mercedes-Benz shows the S-Class Hybrid with the so-called P1/2 drive system. It combines a powerful CDI diesel engine with two electric motors. The eight-cylinder CDI develops 191 kW (260 hp) and a maximum torque of 560 Newton meters. The two electric motors together generate 50 kW so that the vehicle has maximum power of 241 kW (340 hp). This makes the S-Class sprint from stand-still to 100 km/h in 7.6 seconds - tops for hybrid vehicles.

2005 - Economical traveling in a long-distance test through the USA

The world-record-setting diesel sedans again show what they can do during a long-distance journey carried out under everyday conditions. In the summer of 2005 this test takes place on highways in the south of the United States. The E 320 CDI sedans make do with an average five liters of diesel fuel per 100 kilometers (47 mpg) on their trip through Texas, Louisiana, Mississippi, Alabama and Florida. In another six-day test drive through the USA from Las Vegas to Chicago in the summer of 2005, despite differences in altitude of altogether 23,000 meters (75,400 ft), the E 320 CDI merely requires an average 7.1 liters of diesel per 100 kilometers on the selected route (33.1 mpg).

2005 - Bionic research car

DaimlerChrysler launch their BLUETEC initiative for passenger cars in 2005 at the Innovation Symposium in Washington by presenting the bionic car. The bionic mobile is a research vehicle whose exterior shape makes use of the aerodynamic principles of nature. But the drive also has to be maximally environment-friendly, and so the engineers introduce the SCR technology for passenger cars in this vehicle. The engine of the bionic car is a four-cylinder turbodiesel with common rail direct injection and a displacement of two liters. This diesel engine develops 103 kW (140 hp) and consumes 4.3 liters of fuel per 100 kilometers (54.65 mpg) in the standardized European driving cycle. An impressive feature is the more than 80 percent reduction in nitrogen oxides versus production vehicles. This is made possible by the first-time use of SCR (Selective Catalytic Reduction) technology in a car. In the bionic car the designers opt for AdBlue injection; the reservoir is space-savingly accommodated in the spare wheel recess of the concept car. Its filling suffices to cover a distance equal to the servicing interval of an up-to-date diesel engine from Mercedes-Benz.

2005 - S 320 BLUETEC Hybrid

At the 2005 International Motor Show in Frankfurt/Main, Mercedes-Benz presents the S-Class S 320 BLUETEC Hybrid as a luxury-class vehicle in which the low-emission BLUETEC diesel with SCR technology provides the basis for an ultramodern hybrid drive. The electric motor of the hybrid vehicle is integrated into the drivetrain.

2006 - GTL Demonstrator

In 2006 Mercedes-Benz creates the GTL Demonstrator test car on the basis of the E 320 CDI. It offers extremely clean combustion thanks to a tailor-made fuel manufactured from liquefied natural gas (gas to liquid, GTL). Even without aftertreatment of the nitrogen oxides, the car achieves emission levels far below any of the current limits. However, GTL diesel in larger quantities will not be available at filling stations until some time in the future.

2006 - Synthetic fuel

To further expedite the use of synthetic fuels, in March 2006 DaimlerChrysler, Renault, Royal Dutch Shell, Sasol Chevron and Volkswagen form the "Alliance for Synthetic Fuels in Europe" (ASFE). The synthetic fuels include SunDiesel, obtained from organic matter (biomass to liquid, BTL), and synthetic GTL diesel, obtained from natu-ral gas. Synthetic fuels are already contributing to the reduction of emissions. The aim is to better utilize this potential with more advanced technology.

2006 - E-Class SunDiesel

At the Challenge Bibendum in Paris, besides other vehicles Mercedes-Benz shows an E-Class which operates on the BTL fuel SunDiesel. The use of such biogenic fuels causes no additional carbon dioxide to be released, as combustion produces only as much carbon dioxide as was absorbed by the plants during their growth. BTL diesel thus improves the CO2 balance by as much as 90 percent compared with conventional diesel fuel. And there are no technical limits to the use of SunDiesel.

In addition, in Paris DaimlerChrysler displays a concept car - the smart fortwo cdi hybrid - in which a diesel drive and electric motor work together. The consumption of the smart fortwo cdi hybrid is expected to be about 2.9 liters of diesel per 100 kilometers (81 mpg), obtained with a sprightly driving style.

Diesel landmarks and Mercedes-Benz

1892 - Patent on the diesel engine

In 1892 Rudolf Diesel applies for a patent for his engine, which is granted on February 23, 1893, as DRP 67 207 "on a principle of operation and construction for internal combustion engines." He gets the first successful prototype of a production-standard diesel engine running in 1897. In the cylinder of a diesel engine, fuel is mixed with appreciably more air than in a gasoline-powered engine. This makes for very efficient combustion. In addition, the diesel engines require no sparkplugs since diesel fuel with its very good ignition qualities, or rather the air-fuel mixture, ignites spontaneously owing to the very high compression ratio - this is why it is also called the compression-ignition engine. Ignition is triggered off by the sharp rise in temperature during the compression stroke of the piston.

1908 - Afterchamber diesel

At the Deutz company, Prosper L'Orange develops an injection pump for diesel engines and enlarges the combustion chamber with an afterchamber to improve mixture formation. In 1908 he submits a patent application for the afterchamber diesel engine.

1909 - Prechamber diesel

In experiments which he carries out as head of engine testing at Benz & Cie., L'Orange further improves his engine. A new cylinder head shape with a hemispherical chamber now takes the place of the after-chamber. In this so-called prechamber, following injection a small portion of the diesel fuel burns, generating high pressure and propelling the remaining air-diesel mixture into the cylinder where it gets swirled. The pressure and the mixing action permit rapid combustion at high temperatures and thus higher engine speeds. On March 14, 1909, L'Orange files a patent application (DRP 230 517) for the prechamber system.

1919 - Funnel prechamber

Prosper L'Orange changes the shape of his prechamber in 1919 by using a funnel-shaped insert to set it off more clearly from the combustion chamber proper. This way he achieves reliable ignition and good combustion under different loads. He takes out a patent on it on March 18, 1919 (DRP 397 142).

1919 - Pintle-type injection nozzle

Parallel to the funnel prechamber, L'Orange designs a new injection nozzle for more reliable introduction of fuel into the cylinder.

1921 - Variable injection pump

The variable injection pump permits infinite variation of the delivered quantity of fuel, thus enabling precision control of power delivery. The injection pump introduced in 1921 is the last vital component developed by L'Orange for the first diesel engine to see use in vehicles.

1922 - Benz and Sendling introduce the S6 farm tractor

The S6 farm tractor, featuring an 18 kW (25 hp) two-cylinder pre-chamber diesel with a rated speed of 800 rpm, serves to launch the diesel's career as a vehicle drive.

1923 - Benz prechamber diesel

The first of three prototypes of the OB2 truck diesel engine is running on a test bench as early as September 1922. In October Benz installs the four-cylinder into a 5 K 3 chassis, and in spring 1923 the decision is made to produce it: the world's first diesel truck develops 33 - 37 kW (45 - 50 hp) at 1000 rpm.

1923 - Daimler air-injection diesel

In competition to L'Orange's prechamber diesel, Daimler-Motoren-Gesellschaft (DMG) develops an air-injection diesel engine for its trucks. This unit is based on experience gained from the manufacture of submarine diesel engines employing the air injection principle.

1927 - Bosch injection pump

The injection pump introduced by Robert Bosch for diesel engines in 1927 is systematically improved as against older systems. With this injection pump, Bosch, himself one of the first buyers of a diesel truck in 1924, greatly furthers the acceptance of the diesel drive.

1928 - First Mercedes-Benz diesel tractorbr> A new Mercedes-Benz single-cylinder diesel engine is first used in the OE tractor.

1932 - OM 59 in the new Lo 2000 truck

The compact OM 59 prechamber diesel powers the new Lo 2000 express truck.

1935 - 10,000th commercial vehicle with diesel engine

The 10,000th Mercedes-Benz commercial vehicle with diesel engine is built in Gaggenau in 1935.

1936 - Four-cylinder diesel for passenger cars

The Mercedes-Benz 260 D is the world's first diesel passenger car. It is equipped with the OM 138 engine, developed from a truck diesel. The unit has four cylinders, a displacement of 2.6 liters and an output of 33 kW (45 hp).

1940 - Start of development of the 300 engine series

Mercedes-Benz begins developing the new 300 engine series for commercial vehicles during the Second World War.

1949 - Premiere of the OM 312

The six-cylinder in-line OM 312 is the first representative of the new series, debuting in 1949. The 300 engine family in the commercial vehicles of Mercedes-Benz extends its career into the new millennium.

1953 - Exhaust-gas turbocharger in the commercial vehicle

In a fire engine, in 1953 Mercedes-Benz presents its first turbocharged production diesel engine. Its output is about 25 percent higher than that of a naturally aspirated engine.

1964 - First direct-injection diesel engines for commercial vehicles<7b>

The OM 352 is the first diesel engine for Mercedes-Benz commercial vehicles to have direct injection. The economical and performance-enhancing injection system with four-hole nozzle quickly becomes generally accepted in trucks and other commercial vehicles.

1966 - Turbocharging in the OM 352 A commercial vehicle diesel

To attain higher outputs for fuel-injected diesel engines in commercial vehicles, Mercedes-Benz offers the OM 352 A engine with exhaust-gas turbocharger for the first time in 1966.

1969 - The 100,000th commercial vehicle diesel engine

In Mannheim Mercedes-Benz build their 100,000th diesel engine for commercial vehicles in 1969.

1970 - New OM 400 engine series

Mercedes-Benz introduces the new 400 engine series for heavy-duty commercial vehicles in 1970. The first is a V10, which is joined later by V8, V6 and six-cylinder in-line units.

1974 - Five-cylinder diesel in a car

The five-cylinder in-line OM 617 with a displacement of 3,005 cubic centimeters is the first five-cylinder diesel engine in the world to be used in a passenger car. The engine premieres in the Mercedes-Benz 240 D 3.0 (W 115 series).

1977 - S-Class with diesel engine and exhaust-gas turbocharger

In the 300 SD S-Class model, Mercedes-Benz presents a diesel engine with exhaust-gas turbocharger for the first time. With an output of 85 kW (115 hp) and torque of 250 Newton meters, the 300 SD is offered exclusively for the US market. The 300 T Turbodiesel as turbo-charged diesel model which is also sold in Europe does not follow until 1980.

1980 - Intercooler in the OM 422 AL

In 1980, Mercedes-Benz introduces intercooling (charge air cooling) to complement the turbocharger in the new OM 422 AL engine for heavy-duty trucks. Cooling results in more oxygen in the intake air and in higher power output during combustion.

1983 - Engine encapsulation in the compact class for noise insulation

In the diesel models of the compact class launched in 1982 (W 201 series), the engine is fully encapsulated for the first time. This reduces the noise produced by the drive system by about half. Colloquially, the engine design is dubbed the "whisper diesel."

1985 - Particulate trap

In 1985, Mercedes-Benz is the first automotive brand in the world to supply diesel sedans with a particulate trap system as an optional extra to California. The experience gained from this program is the basis for developing new filter technologies.

1989 - "Diesel '89" initiative

In 1989, Mercedes-Benz presents revised engines which cut particulate emissions by around 40 percent. Their features include a new pre-chamber with oblique fuel injection, which enables more efficient combustion. The diesel technology improvement program under which these engines are developed is called the "Diesel '89" initiative.

1991 - Emission control system

The exhaust gases of a diesel engine are markedly different from those of a gasoline-fired engine. While the diesel engine gives off less carbon dioxide, its exhaust gas contains a higher proportion of nitrogen oxides. In 1991 Mercedes-Benz reduces these pollutants with an emission control system employing exhaust-gas recirculation and an oxidation-type catalytic converter. This combination lowers the temperature in the combustion chamber and reduces the formation of nitrogen oxides by about 70 percent. Initially offered as an optional extra, the emission control system becomes standard equipment in 1993.

1993 - Four-valve-per-cylinder design and Electronic Diesel Control

Four-valve technology arrives in the diesel segment in 1993 when Mercedes-Benz introduces the first car diesel engine with four valves per cylinder and electronic control. Four-valve technology gives the diesel engine higher power and better economy than the previous two-valve design. Electronic Diesel Control (EDC) sees use in production vehicles beginning in 1995 when Mercedes-Benz introduces the 2.9-liter direct-injection diesel engine.

1996 - Debut of new commercial vehicle engines

Two new engine series for commercial vehicles are introduced at once by Mercedes-Benz in 1996. The OM 500 diesel V-engines operate in the new heavy-duty Actros truck; the OM 900 in-line engine generation is used in the light-duty Atego truck.

1997 - Common rail direct injection (CDI)

The CDI age begins in 1997. The acronym stands for "Common Rail Direct Injection." Developed by Daimler-Benz in cooperation with Bosch, this direct fuel injection system works with a common fuel line (common rail). Whereas conventional direct injection engines build up pressure for every injection operation anew, in the common rail high pressure is permanently generated, enabling the fuel to be forced to the variable and very precisely controlled injection nozzles at a pressure of up to 1,350 bar. CDI makes the diesel engine a model of high performance, excellent torque already in the lower rev range, great fuel economy, minimal pollutant emissions, and generation of little noise.

1998 - Diesel-electric drive system in the Cito

The Mercedes-Benz Cito is an innovative midibus with a diesel-electric drive in which an OM 904 LA diesel engine powers a generator which supplies energy to the electric traction motor.

2002 - Second-generation CDI

The second generation of CDI technology in 2002 once again improves performance, consumption, comfort and emissions. To achieve this, among other things the Mercedes engineers raise the ignition pressure from 145 bar to 155 bar to optimize the gas cycle. The result is greater pulling power and flexibility. The injection pressure of now 1,600 bar, in conjunction with the newly developed seven-hole injection nozzle, permits finer distribution of the fuel in the combustion chambers, better mixture formation, and more homogeneous combustion.

2003 - First AdBlue filling station in Stuttgart

As first harbinger of BLUETEC, an AdBlue filling station is opened in Stuttgart in 2003. AdBlue - an aqueous urea solution - is injected into the exhaust-gas flow in the SCR (Selective Catalytic Reduction) process. A catalytic converter then reduces the nitrogen oxides in the pre-treated exhaust gas to nitrogen and water vapor. SCR is part of the BLUETEC system for uncompromising reduction of diesel emissions. From 2005, step by step DaimlerChrysler changes over the entire truck and bus range so that the vehicles comply with the EURO IV and EURO V standards.

2003 - Maintenance-free diesel particulate trap

In 2003 Mercedes-Benz introduces maintenance-free particulate traps for diesel engines. Initially the filters are optional equipment. In the summer of 2005, more than 30 car models of Mercedes-Benz, from the A-Class to the S-Class, are fitted with a particulate trap as stan-dard. In the fall of 2005, the manufacture of retrofit kits for vehicles produced before this breakpoint begins, initially for the C- and E-Class.

2003 - Diesel hybrid

In 2003 the F 500 Mind research car presents a hybrid drive combin-ing a V8 diesel engine with an electric motor. The diesel attains an output of 184 kW (250 hp) and maximum torque of 560 Newton meters, and the electric motor adds another 50 kW and 300 Newton meters maximum torque. Electronic control of the link between the two drive units lets each bring its specific advantages into play. Whereas the electric motor can move the car on its own for starting off, parking and slow-speed driving, the strong diesel engine is engaged when more power is required. The union of the two drive systems demonstrates its value particularly in urban traffic.

In the Vision Grand Sports Tourer 2 in 2004 Mercedes-Benz also shows a diesel hybrid drive. The V8 diesel with four liters displacement and 184 kW (250 hp) is again coupled with a 50-kW electric motor. In 2005 the S-Class Hybrid (NAIAS in Detroit) and the S-Class BLUETEC Hybrid (IAA in Frankfurt/Main) follow. To further develop such combi-nations of internal combustion engines and electric motors, DaimlerChrysler cooperates with General Motors and the BMW Group; the three companies enter into an alliance in September 2005. The objective of research is formulated in a Memorandum of Understanding on the joint development of the hybrid drive.

2004 - Introduction of BLUETEC truck with OM 500 for EURO IV and EURO V

In 2004 Mercedes-Benz introduces trucks with OM 500 engines and BLUETEC technology for emission control. These vehicles meet the especially stringent EURO IV and EURO V emissions norms. As early as February 2006, delivery of the 10,000th BLUETEC truck with EURO V engine takes place.

2005 - Third-generation CDI

A new high-tech V6 diesel engine marks the beginning of the third generation of CDI technology at Mercedes-Benz. Owing to new materials and optimization of the entire unit, the new CDI engines attain even higher combustion pressures than before - the engineers aim at up to 200 bar and intend to boost the injection pressure too in future, to as high as 2,000 bar. In addition, the complex CDI technology is further refined. The fuel is no longer injected all at once, but in as many as five portions. Special actuators (piezo crystals) take over the control of the injection nozzles: with electric pulses the atomic structure of the crystals can be expanded several hundred thousand times per second if required. With this sophisticated injection system, not only are the emissions further reduced; the working noise of the engine is also diminished once more.

2006 - BLUETEC for passenger cars

In 2006, Mercedes-Benz introduces BLUETEC for passenger cars to the market in an E-Class. The technology for the cleanest diesel in the world has been successfully used in commercial vehicles since 2005. The Mercedes-Benz E 320 BLUETEC is the first representative of a new generation of diesel cars of the Stuttgart brand on this technical basis. From the fall of 2006 the E 320 BLUETEC goes to market in the USA; the market launch in Europe is scheduled for 2008.

Under development since 2002, the BLUETEC modular technology package relies on several means of reducing diesel emissions. On the one hand, these include familiar methods like the oxidation-type catalytic converter and particulate trap, along with optimized engines. But the heart of the system is the actual BLUETEC technology for nitrogen oxide reduction. In the first production car equipped with it, the E 320 BLUETEC, there is a complex catalytic converter system consisting of an improved nitrogen-oxide storage-type catalytic converter and an SCR catalytic converter. In normal operation the nitrogen oxides in the exhaust gas are collected in this catalytic circuit. Regular adjustments to the air-fuel mixture in the engine change combustion, and with it the composition of the exhaust gases, for a brief period. In the process, BLUETEC separates the stored nitrogen oxides into nitrogen and water vapor.

More complex, but more effective still is Selective Catalytic Reduction (SCR) by means of AdBlue injection. When AdBlue is injected into the pretreated exhaust gas, ammonia is released which then causes reduction of nitrogen oxides to harmless nitrogen and water in the downstream SCR catalytic converter. Spraying this aqueous urea solu-tion into the exhaust-gas flow is currently the most efficient method of exhaust-gas aftertreatment for diesel engines. This system can reduce nitrogen oxides by as much as 80 percent. With the Vision GL 320 BLUETEC, Mercedes-Benz engineers demonstrate in 2006 that this too is a process that can find use in large-scale production. In the fall of 2006, the E 320 BLUETEC production car finally appears.

BLUETEC technology has been very successfully employed in Mercedes-Benz commercial vehicles in Europe since 2005. In the meantime this technology has performed outstandingly in more than 20,000 Actros, Axor and Atego trucks. BLUETEC cuts nitrogen oxides so sharply that the emissions limits applicable to trucks from 2009 are already undercut today. This is rewarded with lower road tolls for trucks with EURO V technology through 2009. Whereas AdBlue for cars might be replenished during a service stop, a comprehensive network of AdBlue filling pumps for commercial vehicles is available in Europe.