World Record for Mercedes E 320 CDI: In Detail

Press Release

100,000 miles at world-record speed

Mercedes-Benz has set a new diesel world record and has once again succeeded in highlighting the performance, reliability and environmental compatibility of today's advanced diesel engines. The three standard-production Mercedes-Benz E 320 CDI models completed the 30-day, 100,000-mile, marathon at an average speed of 139,699 mph (224,823 km/h) without suffering any problems.

Mercedes-Benz set three cars at once on course for a record at the high-speed circuit in Laredo, Texas; all three successfully covered the record distance, thereby providing proof of the E- Class's reliability three times over. To do so each of the three candidates did no fewer than 20,000 laps. Adding up the distances covered by all three cars gives an impressive total of 300,000 miles (482,802 kilometres) – one-and-a-quarter times the distance from the Earth to the Moon. In addition to their powertrain, their chassis and body structure was also pushed to the limit. Dramatic climatic variations, with temperatures up to 45°C (113° F) and the con-tinuous vibration caused by the uneven road surface provided additional challenges for the vehicles. This ordeal proved the durability of the new, 165 kW/224 hp V6 CDI diesel engine as well as the seven-speed 7G-TRONIC automatic trans-mission. This world-record run allows premium manufacturer Mercedes-Benz to demonstrate once again that today's diesel engines are among the most advanced drive systems available. Among those who became convinced by the new V6 CDI powerplant was Brendan Gaughan, who last season drove in the most successful US racing series, the NASCAR Nextel Cup. "For a diesel to manage a distance of four times round the world at an average speed of 139.699 mph is fantastic. What impressed me, in addition to this sporting achievement, was its great smoothness and comfort – both were on a par with a V8 gas engine."

The world-record run was supervised by the FIA*, which sets and enforces strict rules for tests of this kind. The participating vehicles were selected at Daimler-Chrysler's Sindelfingen plant before they even left the production line by FIA officials who sealed them before they were shipped to the USA. Before, during and after the record run, the test vehicles were monitored continuously by the FIA until the world record was recognized officially. In accordance with the globally recognized regulations, the extent of any repairs which may be performed is limited and the replacement of entire assemblies such as the engine, transmission or exhaust system is not allowed. The test vehicles had no difficulty in meeting these requirements as no faults occurred during the record run. In addition to numerous class records, the three six-man driver teams also set new world records for 50,000 miles at 140.092 mph (225.456 km/h) and for 100,000 miles at 139,699 mph (224.823 km/h). **

As well as offering superb performance and excellent quality, these vehicles are also outstandingly economical. The fuel consumption figure of 40 mpg achieved by the E 320 CDI under normal driving conditions is unrivalled by any vehicle in its competitive segment in the USA. Furthermore, the Mercedes-Benz engineers have successfully used effective emission control systems to satisfy the strict exhaust emission standards set by the EPA. Through the use of the latest technology it will in future be possible to comply with the Californian CARB (California Air Resources Board) legislation – the strictest in the world – which currently applies in five states. In view of the dramatic rise in fuel prices, US President George W. Bush last week announced a programme to develop more fuel-efficient, low-emission vehicles. Together with hybrid vehicles, "clean diesel" models like the Mercedes-Benz E 320 CDI are to be promoted by means of tax incentives to the tune of $ 2.5 billion over the next few years.

The potential fuel savings which could be achieved through increased adoption of diesel engines in the USA are enormous. An increase in the proportion of diesel-powered cars and light commercial vehicles from the present one percent to 50 percent as in western Europe would save the USA approximately 2.3 million barrels of crude oil per day. The amount saved on an annual basis is even more impressive: requirements of crude oil would be slashed by 839 million barrels, or around 133 billion litres. Many American consumers are already convinced of the benefits of today's advanced diesel powerplants, as demonstrated by the response to the launch of the Mercedes-Benz E 320 CDI. The planned sales volume of 3000 vehicles in 2004 was attained after just five months. And the customers are de-lighted, especially by the sporty and agile performance, the good fuel economy and the high level of comfort. In those federal states in which Mercedes-Benz offered the E-Class with diesel engines, just under 12 percent of customers opted for a diesel model.

Mercedes-Benz is regarded as the pioneer of diesel technology. As early as 1936, the company officially presented the world's first standard-production diesel pas-senger car in the form of the 260 D, the first prototypes having successfully un-dergone endurance road trials the previous year. Another milestone on the way to today's advanced, agile diesel powerplants was the introduction of turbo technology in the seventies. As early as 1985, the company presented the world's first particulate filter, while the premiere of the common-rail diesel followed in 1997. The consistent effort which Mercedes-Benz has put into the evolution of diesel technology over the last 70 years has helped it attain the high regard which it en-joys around the world today. Future developments by the Stuttgart-based com-pany will make the diesel even more attractive, powerful and environmentally compatible. This commitment is acknowledged by customers: Mercedes-Benz has already delivered more than seven million diesel-engined passenger cars to date. The overall share of diesels within the Mercedes-Benz model range worldwide now lies at 35 percent, and in western Europe is even as much as 56 percent.

* The Paris-based FIA (Fédération Internationale de l´automobile) is acknowledged as the governing body for world-record attempts in the automotive sector
** World records subject to confirmation by the FIA

On track for a record-breaking career

· Around the world - four times over

· The world-record run by the E 320 CDI

The start of the world-record run on April 1st, 2005, marked the beginning of one of the toughest tests ever inflicted on a standard-production vehicle. Long-distance world-record attempts are nothing new, but no manufacturer has ever dared to go for a record with three diesel-powered vehicles over a distance of 100,000 miles (160,934 kilometres) each. The figures associated with the test bring home the daunting scale of the event: 100,000 miles covered at an average speed in excess 139,699 mph (224,823 km/h), 24 hours a day for 30 days.

Adding up the distances covered by all three cars gives an impressive total of 300,000 miles (482,802 kilometres) – one-and-a-quarter times the distance from the Earth to the Moon. In order to lend the record runs additional authority, Mer-cedes-Benz used three E 320 CDI models whose only distinguishing features consisted of red, green and blue markings with similarly coloured front fog lamps. The fact that no fewer than three cars managed the record distance is a clear indication of how reliable the current E-Class is. The vehicles were driven by three teams of six drivers, with each driver taking the wheel for about 2 hours, 10 minutes between refuelling stops. Servicing, involving the replacement of operating fluids and wear parts, was performed usual in accordance with the service inter-vals. Each vehicle required servicing 10 times in the course of the entire record run.

Summarised "technical data" of the record-breaking drive:

May 1st, 2005 saw the vehicles cross the finish line and take their well-deserved place in the record books. Like a high-precision Swiss watch mechanism, the E 320 CDI models did all that was asked of them without any problems. The most outstanding aspect of this record run is that the 100,000 miles (160,934 kilometres) were covered at an average speed of 224.823 km/h (139.699 mph)***. Mercedes-Benz succeeded in breaking all 22 of the international FIA records which it had set out to break.

* International FIA records in vehicle category B – production vehicles, Group III – turbo-diesels, Class 11 – swept volume 2,500 – 3,000 cc
** World record: absolute best figure among all vehicle categories and classes
*** All records subject to confirmation by the FIA Records Commission
**** 1 mile = 1.609344 km (conversion factor according to FIA rules)

From production line to world-record circuit

 

Record-breaking Mercedes-Benz E 320 CDI is a production model

 

The three Mercedes-Benz E 320 CDI models involved in the world-record run in Laredo, Texas, set out to prove that perfectly standard products from Mercedes-Benz are outstandingly durable, even when subjected to the most extreme stresses. The fact that no fewer than three vehicles set out to set a record was for a simple reason: it proved the reliability of today's E-Class three times over. Areas of special interest were the powertrain with the newly developed V6 diesel engine and 7G-TRONIC automatic transmission as well as peripheral assemblies such as the fuel system, engine management system and, in particular, the entire exhaust system with its diesel particulate filter. The only modifications to the record vehicles involved the installation of an interior roll-over bar. In addition, coloured plastic sheeting was affixed to each car, and the fog lamps and exterior mirrors were coloured for easy identification.

 

Before the record run could start, Mercedes-Benz had to satisfy a number of conditions imposed by the FIA. The first of these involved compliance with the Category B, Group 3, Class 11 classification of the vehicles. This means that that the record bid had to be conducted using standard-production vehicles powered by a turbodiesel engine with a maximum displacement of 3 litres. Furthermore, an accurate list indicating the records which were being targeted had to be prepared. A total of 22 international FIA records were specified, ranging from the 10-kilometre short distance to the final long-distance targets of 100,000 kilometres and 100,000 miles (160.934 kilometres). In accordance with the vehicle classification, an official from the DMSB (Deutscher Motorsport-Bund), the German body representing the FIA, chose nine new E 320 CDI models from a random group of vehicles on the assembly line in Sindelfingen; tamper-proof seals were applied to these vehicles. The nine cars were allowed to be run-in briefly by Mercedes-Benz employees under the supervision of the FIA official. Three vehicle were then selected from the group of nine, fitted with a roll-over bar and marked in different colours. They were then tamper-sealed once again before being transported to Laredo. Here, too, they were under the constant supervision of FIA* officials.     

 

Strict rules for world-record bid

 

Stewards and Technical Observers from the USAC (United States Auto Club) are also on hand to monitor events at the Texan test track throughout the 30 days of the record bid. They report to the ACCUS (Automobile Competition Committee for the United States), which in turn represents the FIA* as a local national body. Strict limits are set for the scope of repairs during the run: the replacement of entire assemblies such as the engine or transmission is prohibited. And limitations also apply to any repairs over and above the usual servicing activities or the replacement of lubricants and wearing parts. Before the start of the record attempt, the Mercedes engineers had to specify replacement parts which are kept in an FIA*-sealed container next to the track. The vehicles participating in the record bid have to carry a weight equivalent to that of these replacement parts, limited to 5% of the vehicle weight plus 20 kg, at all times. And, of course, the record clock keeps running during refuelling stops, servicing and any repairs which may be necessary. As a further hurdle during record-breaking bids with standard-production vehicles, additional measuring or transmitting systems such as telemetry are not permitted. Only the standard diagnostic software which can be found in Mercedes-Benz workshops may be used.

 

* The Paris-based FIA (Fédération Internationale de l´automobile) is acknowledged as the

   governing body for world-record attempts in the automotive sector

 

 

E 320 CDI: Overview of technical data

 

 

Laredo – the venue for the world record

 

Torture in a good cause

 

The surroundings look more like the setting for a remake of a classic western than the venue for an automotive world record. The Auto Testing Properties Laredo (ATP Laredo for short) proving ground is situated in the middle of the Texan prairie, not far from the border city of Laredo on the Rio Grande. At first glance, the test site would seem to offer optimum conditions for conducting a world-record bid with average speeds in excess of 200 km/h. And with an annual count of 320 days of sunshine and an average temperature of 23.5 degrees Celsius, the climatic conditions also seem ideal. 

 

Heat, dust and a bumpy circuit

 

But a closer examination soon reveals that the ATP Laredo facility is subject to a number of factors which are more likely to be detrimental to the vehicles and engines involved in a world-record bid. Daytime temperatures in March are already over 30 degrees Celsius while the nights are decidedly chilly. Whenever the wind picks up it drives a large amount of dust into the air, thereby putting particular demands on the filter systems for the engine and passenger compartment which, like every other aspect of the vehicles, have to demonstrate their effectiveness throughout the 30-day record run. The repertoire of this somewhat uneven circuit also includes potholes, cracks and bumps which ensure that the vehicles will be subject to continuous shaking and vibration over the entire record distance. The five-mile circuit with its slightly banked curves does not even out lateral forces, so the drivers constantly have to make steering corrections. The lateral forces acting on the car all the time mean that the steering system and front suspension are subject to severe stresses and strains.

 

A link in the worldwide network of DaimlerChrysler test facilities

 

Covering an area of some 810 hectares, the ATP Laredo facility is one of the larger test sites in the worldwide network of test sites owned by DaimlerChrysler. In addition to its high-speed circuit, the facility features a two-mile (3.22 km) oval and a very wide range of torture tracks such as undulating block sections, coarse cobbled roads, mud tracks, potholed tracks, splash troughs, off-road sections and steep grades. A handling section and various circular surfaces for driving dynamics testing complete the list of test facilities.

 

Set up in 1963 by United States Rubber Company, the facility was taken over by tyre manufacturer Michelin in 1990 before it went on to be integrated in the worldwide DaimlerChrysler network as ATP Laredo in 1998. Some six million dollars have been invested in the modernisation of the site since it was taken over.  

 

New V6 diesel engine from Mercedes-Benz

 

Agility and driving pleasure as standard

 

The concept of diesel driving pleasure achieves a new quality with the new CDI engine. As the successor to the five and six-cylinder in-line engines it offers an increase in output and torque of up to 38 percent, ensuring faster acceleration, brisk intermediate sprints and a higher top speed. The maximum torque of 510 Newton metres is already available from 1600 rpm, and remains constant up to 2800 rpm. Accordingly the new V6 has torque characteristics which are unsurpassed in this displacement class. In combination with the unique 7G-TRONIC seven-speed automatic transmission, this ensures the best possible exploitation of the remarkable output and torque potential in any driving situation.

 

Despite a significantly higher output, the fuel consumption remains at the exemplary level of the previous five and six-cylinder diesel engines.

 

The choice of materials, design, fuel injection and engine management system reflect the state of the art. As a world first for a diesel engine in this displacement and output class, Mercedes-Benz has developed an aluminium crankcase with cast-in grey iron cylinder liners for this unit which makes a major contribution to weight reduction. As a result, the new V6 weighs a total of only approx. 208 kilograms (acc. to DIN) and is therefore only very slightly heavier than the previous five-cylinder engine. The power-to-weight ratio has increased by more than 20 percent to 0.79 kW/kg – a major contribution to the outstanding diesel agility offered by the new engine. The engine block, components and ancillary units form a very compact entity, which means that in future the new V6 will also be installed in Mercedes model series and 4MATIC variants where no six-cylinder diesel engine was previously offered.

 

Fuel injection at 1600 bar and innovative piezo injectors

 

Mercedes engineers have refined the common-rail direct injection system, achieving further progress in fuel consumption, exhaust emissions and combustion noise with this third-generation technology. Newly developed piezo injectors work much faster and more precisely than the previous solenoid valves and ensure the fuel supply to the cylinders is very accurately metered. This allows the fuel injection to be even more precisely adjusted to the current load and engine speed, and now makes five injections per power stroke possible at a peak pressure of up to 1600 bar.

 

Electrically controlled intake port shut-off modifies the turbulence of the intake air as it enters the cylinders, optimising the combustion process with the aim of further reducing the fuel consumption and exhaust emissions. The likewise new electronic control unit manages all the engine functions – from the quick-start glow system and automatic start function to control of the high-pressure pump. The VNT turbocharger (Variable Nozzle Turbine) with electrically adjustable turbine blades, exhaust gas recirculation with a control valve and intake air throttling are regulated as the situation requires on the basis of measured data. In addition the microprocessor exchanges data with the seven-speed automatic transmission and the Electronic Stability Program.

"We're the first to dare to embark on a challenge like this"

 

Interview with Dr. Michael Krämer

Member of the Directors' Board

Spokesman for the management team C-Class/E-Class

Head of passenger car development C-Class/E-Class

 

? The diesel market is booming in Europe, but is only of secondary importance in the USA. What are the reasons for this?

 

! Up till now, people in the USA just aren't aware of the advantages of today's diesel engines. With campaigns like our diesel initiative we aim to reinforce the image of this type of propulsion as a powerful, economical, clean and dynamic alternative to the petrol engine.

 

? Just how has the diesel engine changed over recent years?

 

! The fact that the diesel engine is now an up-to-date, user-friendly engine with convincing performance and outstanding environmental credentials is a consequence of our consistent policy of developing and enhancing the fuel injection, timing and exhaust gas aftertreatment systems. What one might perhaps call evolution rather than revolution. Not that we have interfered with the DNA of the diesel engine. Reliability and proverbial durability still number among the outstanding characteristics of Mercedes diesel powerplants. In the case of our CDI engines, for example, our investment in research and development alone has amounted to about two billion euros over the past few years.

 

? How can American consumers be made more amenable to the diesel engine?

 

! We have to make the advantages of today's advanced diesel engines clear to them. This can be done by means of initiatives such as the world-record run by a standard-production E 320 CDI in Laredo in Texas under FIA* conditions. Just think: a record run of 100,000 miles, in a vehicle driven 24 hours a day for 30 days at an average speed of more than 130mph (220 km/h) – we're the first to have ever attempted such a feat. And, of course, we're using an oxidising catalytic converter as well as a diesel particulate filter and we are going to comply with the strict EU 4 exhaust emission limits throughout the entire record distance. Alongside numerous other measures, this record-breaking achievement will help us to emphasise the positive characteristics of today's diesel-powered vehicles and anchor them firmly in the minds of the American public.

 

* The Paris-based FIA (Fédération Internationale de l´automobile) is acknowledged as the governing body for world-record attempts in the automotive sector

 

? What conditions does the FIA set for a world-record attempt like this?

 

! Plenty! First of all, we have to submit a detailed description of the record drive. Then an official, in our case a member of the Deutscher Motor Sport Bund as the body representing the FIA in Germany, selects the vehicles to be used for the record bid at the end of the production line. The vehicles are sealed, taken to the test circuit under the supervision of the DMSB and handed over to the American officials. For the duration of the record-breaking bid officials from the United States Auto Club are on hand. They act on behalf of ACCUS, which is in turn the body representing the FIA in the country where the record bid is to be made. Moreover, the test circuit has also to be officially measured and approved by the FIA.

 

? Are repairs permitted during the record-breaking drive?

 

! Repairs are only allowed to a limited extent. Complete replacement of the engine or transmission, for instance, is not permitted. Before the start of the record drive we have to define replacement parts, and carry their equivalent in weight the whole time in the cars. The rules limit this weight to around 100 kilograms. This restriction on its own speaks volumes: you must have a highly reliable foundation, such as our E-Class, for record drives of this kind, since major repairs are not possible.

 

?Why don't you just leave a CDI vehicle running on a rolling-road dynamometer for 30 days?

 

! Test-bench simulations are an important tool in the development and testing of new engines, electronics, transmissions etc. But they represent the lab-based side of development and can never replace real-world testing in the actual vehicle. We deliberately chose Laredo in Texas because it offers the toughest conditions for the record run and subjects the entire vehicle – rather than just the engine – to extreme stresses.

 

? What kind of testing does a Mercedes-Benz engine usually have to complete in order to be deemed fit for series production?

 

! In the course of a vehicle's development it is often subjected to even more gruelling requirements than our world record bid – which itself corresponds to more than three times the punishment a car would normally see in the hands of a customer! We test our engines in extensive real-life trials in tropical heat and Arctic cold, in various different model series and on a wide variety of test roads all over the world. Then there are the test-rig runs and laboratory tests I mentioned before.

 

? What other kinds of torture will the vehicles involved in the record bid have to contend with?

 

! To start with, there's the 5-mile high-speed circuit. It's none too recent and anything but smooth. The cars will be continuously shaken by all the potholes, cracks and bumps in it. And then there's the typical desert climate, with temperatures rising to 45 degrees Celsius during the day and then cooling noticeably at night. Depending on the weather, the air can be very dusty, so that will be a challenge not only for the engine, but also for assemblies such as electronics and the entire powertrain, which features our 7G-TRONIC seven-speed automatic transmission, or the chassis.

 

? Moving on to the factors which influence the US market, will the upcoming  US legislation help or hinder diesel-powered vehicles?

 

! On the one hand, diesel and petrol models are subject to the same exhaust emission regulations in the USA. In order to comply with these limits, we would have to use catalytic converters and particulate filters as we do in Europe. On the other hand, the legislation permits diesel fuels with a proportion of sulphur that is up to 33 times than in Europe. The trouble is, sulphur is one of the main factors causing the formation of particulates when diesel fuel is burned. This is impeding the deployment of catalytic converters and particulate filters, and low-sulphur diesel fuels are not scheduled for introduction in the USA until mid-2006.

 

? How great are the savings which could be made if economical, low-emission diesel models were as popular in the North American market as they are in Western Europe?

 

! The savings would be enormous – both for the customer and for the environment. It has been stated in the clearest terms by Margo T. Oge, the Director of the Federal US environmental agency. An increase in the proportion of diesel-powered cars and light commercial vehicles from the present one percent to around thirty percent would save the USA approximately 1.4 million barrels of crude oil per day – equivalent to the entire amount of oil imported by the USA from Saudi Arabia. If we were to assume a 50 percent market share for diesels, as in western Europe, the potential amount saved in a year would be an astronomical 133 billion litres!

 

? In the past, did American drivers avoid buying diesel cars because there were no up-to-date, attractive models on offer, or did the auto manufacturers choose not to offer any diesel models because nobody wanted a car with a diesel engine?

 

! Mercedes-Benz can look back on an extremely successful diesel tradition – which extended to the USA, too. We were successfully offering diesel models there as early as the beginning of the nineteen eighties. Other manufacturers were surprised at this success, but wanted to cash in on the boom in demand which we had triggered as quickly as possible. Unfortunately, these manufacturers moved in with vehicles which were not sufficiently mature or reliable and which damaged the originally positive image of the diesel engine.

 

? What prospects do you see for the future of the diesel engine in the USA?

 

! Our diesel initiative, which I mentioned at the beginning, gives us every reason to be optimistic. Last year saw us offer a diesel passenger car again, the E 320 CDI, for the first time since the nineteen eighties. It was an overwhelming success. Our sales volume of 3000 vehicles planned for 2004 sold out in just five months. The customers were impressed not only by its excellent performance but also by its unbeatable fuel consumption figures. Capable of doing around 40 miles per gallon of diesel- which translates into a fuel consumption of around 5.9 litres per hundred kilometres in European terms - it set a new standard for fuel economy.

 

? Rising fuel prices in the USA are making diesel models with good fuel economy increasingly attractive. Will Mercedes complement its economical diesel models at the higher end of the market with diesel powerplants in the more compact vehicle categories?

 

! The Mercedes-Benz E 320 CDI is, of course, only the beginning of a long-term strategy. This model will enhance the image of diesel vehicles decisively. American customers will follow their European counterparts in associating attributes such as sportiness, agility, economy, comfort, quietness and environment-friendliness with the diesel engine. We will then go on to extend the diesel range substantially in all vehicle classes.

 

The world's strictest exhaust emissions legislation

 

Petrol and diesel vehicles are subject to the same rules in the USA

 

In contrast to the EU standards, the US exhaust emissions regulations laid down in the Clean Air Act do not differentiate between different types of fuel or drive technology. This means that the same standards apply, regardless of whether a vehicle has a petrol, diesel, gas, hybrid, electric or fuel-cell drive system. The level of fleet average emissions of oxides of nitrogen (NOx) is the key parameter which determines compliance. The limits for all the other exhaust components, such as the levels of hydrocarbons, carbon dioxide or particulate emissions are determined on the basis of this central parameter. This arrangement tends to put the diesel engine at a disadvantage as it is inherent in its design that it emits more oxides of nitrogen than a petrol model while its considerably lower carbon dioxide emissions go unacknowledged.

 

There are two different sets of standards. On the one hand, there is the federal legislation which applies in 45 states. The regulatory authority, the EPA (Environmental Protection Agency), classifies vehicles by certification levels known as BINs. These range from BIN 9 and BIN 10, which will be phased out in the 2006 model year, down to BIN 1 for zero-emission vehicles (ZEV). On the other hand, there is the Californian CARB (California Air Resources Board) legislation which currently applies in five states. This classifies vehicles into a number of different categories, such as LEV (Low Emission Vehicle) or ULEV (Ultra Low Emission Vehicle). These standards are even more rigorous than the federal ones.

 

Furthermore, in all the states, vehicle manufacturers have to prove the long-term effectiveness of their exhaust systems by means of field trials. On the basis of the volume of vehicles sold, a certain number of the relevant models have to undergo an extensive laboratory test programme to determine the level of exhaust emissions. The vehicles concerned comprise models which are about one year old and have covered 10,000 miles as well as older models which have covered at least 50,000 miles.

 

Effective exhaust systems smooth the way

 

Irrespective of these certification levels, the coming years will see cars facing more stringent standards which can only be met through the use of an exhaust treatment system. Because of their extremely favourable exhaust emissions profile, Mercedes diesel vehicles can be registered in the 45 states which comply with EPA standards up to the 2006 model year without the need for exhaust treatment technology such as NOx storage catalytic converters or diesel particulate filters. With effect from the 2007 model year, however, the introduction of stricter NOx standards (comparable to those already in force in California) will make it necessary to adopt technology of this kind. Ever more demanding emissions legislation will mean that new measures will have to be taken with effect from the 2009 model year. Thanks to its comprehensive research activities in this field, Mercedes already has various solutions.

 

The fundamental prerequisite: clean diesel fuel

 

The extremely lax laws governing fuel contrast sharply with the stringent exhaust emissions legislation. The high sulphur content of US diesel fuel is a major stumbling block for effective exhaust systems. Systems designed to reduce the level of oxides of nitrogen are particularly vulnerable – to the point where they sustain lasting functional impairment – when diesel containing a significant degree of sulphur is used. Throughout Europe, the permissible sulphur content in diesel has been limited to just 10 ppm (parts per million) since January 2005. In exceptional cases, diesel with up to 50 ppm of sulphur can be authorised. This limit just falls within the bounds of acceptability for today's exhaust systems. However, increased sulphur content leads to more frequent regeneration phases and thus increases fuel consumption.

 

In the USA, it will still be permissible for diesel fuel to contain 500 ppm of sulphur until mid-2006. Thereafter, diesel which complies with a new upper limit set at 15 ppm will be universally available. However, oil companies will still be allowed to sell diesel with higher sulphur content (which will have to be clearly identified on the filling-station pumps concerned) until 2010. Another problem with US diesel is its typical cetane rating – an index for the ignition quality of diesel fuel. A high cetane rating promotes smooth running and thus the comfort of a diesel engine. Whereas Europe's filling stations deliver diesel with a cetane number of about 52, the corresponding figure in the USA is just 44.

 

Synthetic diesel might offer an interesting new dimension of fuel quality in the future. Researchers in both the USA and Europe are working on these fuels produced from natural gas (GTL = Gas To Liquid) or biomass (BTL = Biomass To Liquid). The key benefits of designer diesel are that it is free of sulphur and can offer cetane ratings of up to 80. Bespoke fuels of this kind would result in another major reduction in untreated emissions and increase the effectiveness of exhaust treatment systems such as the NOx storage catalytic converter. 

 

In principle, the US authorities have abandoned their originally restrictive attitude towards passenger cars with diesel engines. It is true that the ever more stringent NOx limits are leading to ever more sophisticated exhaust gas aftertreatment measures. But Mercedes-Benz already has solutions which it can call on to overcome this hurdle, too. Ultimately, however, it is America's car drivers who will decide the future of the passenger-car diesel engine in the USA. Already sought-after for its outstanding environmental compatibility, the years to come will see its sporty and agile performance, excellent comfort and considerable fuel-saving potential secure it an increasing share of the market. The diesel engine will also experience fresh impetus following the latest announcements by the Bush Administration. In view of the dramatic rise in fuel prices, US President George W. Bush last week announced a programme to develop more fuel-efficient, low-emission vehicles. Together with hybrid vehicles, "clean diesel" models like the Mercedes-Benz E 320 CDI are to be promoted by means of tax incentives to the tune of $ 2.5 billion over the next few years.

 

The world's fastest diesels

 

First diesel world record bids took place as early as 1959

 

There is a tradition of world-record bids at Mercedes-Benz. One milestone was the speed record - which stood unbroken for 13 years - set by the "Blitzen Benz" which Bob Burman, an American, took to 141,8 mph (228.1 km/h) in April 1911. In 1938, Rudolf Caracciola set a world speed record of 263,3 mph (423.7 km/h) which remains unbroken to this day when he drove a streamlined W 125 Silver Arrow on the specially cordoned-off Frankfurt-Darmstadt autobahn.

 

Very high speeds were also the priority for the first record bids with Mercedes-Benz diesel engines. The first attempts were made by private teams, some of whose methods were less than conventional. There was a team of four, who were well-known in the field of rallying at the time, who transplanted a modified OM 621 engine (4 cylinders, 2032 cc swept volume, 44 kW/60 hp) into a 190 SL Roadster in 1959 and set a new 24-hour speed record with an impressive 77,1 mph (124.1 km/h). It is particularly notable that this was achieved with a 190 SL soft-top which, in all other respects, was an absolutely standard production model. Two years later, the small two-seater was at it again – only this time it had been optimised radically. A 65 hp diesel powerplant was at work under the bonnet, the body had been stripped of all ornamentation and the windscreen and roof were replaced by a small semicircular screen in front of the driver. Nevertheless, this record-breaking vehicle attained a speed of 88,4 mph (142.3 km/h) over a distance of 5 kilometres with a flying start.

 

The next attempt was made by the well-known motoring journalist

Fritz B. Busch at the end of 1975. The list of ingredients for the "Dieselstar" makes for rather bizarre reading: it was built on the basis of a retired Formula 2 racing car and engine power transfer was provided by a transmission from a De Tomaso Pantera; the body consisted of 25 square metres of sheet aluminium, one square metre of Plexiglas, 100 metres of sectional steel and some 3000 blind rivets. It also used the fuel tank from a Heinkel scooter, a DIY-store magnetic catch and bolt for the entry hatch and a tea strainer ahead of the air intake for the diesel engine. Although there was nothing bizarre about the latter: it came straight from the Mercedes-Benz test department. A turbocharger gave extra boost to the in-line 5-cylinder unit which had a peak output of 114 kW/187 hp. It allowed Fritz B. Busch to attain a maximum speed of 157,7 mph (253.7 km/h) and thus to set the undisputed speed record for diesel vehicles.  

 

C 111-IID sets new standards

 

In 1976, Mercedes-Benz decides to intervene directly to put paid to the old prejudice that diesel engines are lethargic, noisy and less than sporty – and it does so particularly thoroughly. The racy styling and bright orange paint finish of the C 111, which also features gullwing doors, make it the ideal ambassador for a new generation of diesels. The engineers modify the five-cylinder diesel engine from the Mercedes 240 D 3.0 for the record attempts. Now dubbed the C 111-IID, the car is able to get an impressive 190 hp out of what was originally an 80 hp engine – thanks to extra features such as turbocharging and a charge-air cooler. The C 111-IID clocks up some very impressive speeds in June 1976 at the Nardo test track in southern Italy. Overall, the four-strong team of drivers set 16 world records, of which 13 apply to diesel engines, the other three applying to vehicles with any engine type. The records it set were:

  
10 km                       137,115 mph                           220.619 km/h
10 miles                   141,300 mph                           227.353 km/h
100 km                     156,089 mph                           251.148 km/h
100 miles                 157,162 mph                           252.875 km/h
500 km                     157,915 mph                           254.086 km/h
500 miles                 157,197 mph                           252.930 km/h
1000 km                   157,431 mph                           253.307 km/h
1000 miles     ÂÃ&a

The future has already started

 

High-performance diesels in a class of their own

 

The potential of the diesel drive system is as great as ever, despite the fact that considerable progress has been made with regard to practically every aspect of this technology over the past decades. A comparison of the world's first diesel saloon, the Mercedes 260 D of 1935, with today's C 320 CDI provides an indication of how much has been achieved. Over a distance of ˜62 mph (100 km), the 260 D helped itself to no less than 0.3 litres of fuel per kilowatt; the corresponding figure for the C 320 CDI is just 0.04 litres. A similar picture emerges when looking at the power-to-swept volume ratios: the 260 D, the original diesel passenger car, was able to generate 17.7 hp per litre of swept volume; its great grandson, the C 320 CDI, manages an impressive 75 hp.  

Despite this revolutionary progress, the potential of advanced Mercedes-Benz diesel engine technology is still far from being fully exploited. In the Mercedes-Benz labs, engineers are testing new materials for the combustion chamber and continuously working to optimise the chamber’s shape in order to increase combustion pressure in the future. Flow researchers are meanwhile enhancing the swirl of the fuel: the more uniformly the droplets of fuel are distributed within the combustion chamber, the higher the output and the lower the emissions will be. The role played by the injection process is obviously critical, too. Further optimisation of the injectors will see the injection pressure of advanced CDI diesel engines for passenger cars rise from its current level of 1600 bar to 1800 bar and more. Implemented in combination with ever finer nozzle holes, this will result in even finer atomisation and metering of the diesel fuel.

 

A sublime combination: a roadster with a high-performance diesel engine

 

Anyone who thinks that it is impossible to reconcile a roadster and a diesel powerplant has seriously underestimated the latter's development possibilities. As in all other vehicle categories, advanced diesel engines can certainly play a role here, as the Vision SL 400 CDI Biturbo and Vision SLK 320 CDI Triturbo showcars clearly demonstrate. A new V8 engine generates 231 kW/315 hp in the Vision SL 400 CDI and provides the crankshaft with an outstanding torque of 730 Nm. The Vision SLK 320 CDI Triturbo, meanwhile, can generate an impressive 210 kW/286 hp and 630 Nm of torque from three litres of displacement (70.3 kW and 211 Nm per litre of displacement).

 

The SLK 320 CDI Triturbo is based on the new V6 diesel engine, which achieves new levels of performance thanks to a two-stage supercharging system. It consists of three turbochargers, of which two are located on the outside next to the cylinder banks while the larger third turbocharger is situated in the V of the cylinders. At low engine speeds and loads, air flows through all three turbochargers with the small turbochargers doing most of the work. When engine speed increases and the flow is continuous, the large turbocharger takes over supplying the greatest share of the charge pressure. At the upper end of the rev range at full load, only the large turbocharger is in operation. The three turbochargers give the Roadster exceptional performance which is reflected by its self-assured looks which it shares with the SLK 55 AMG: it takes the car just 5.3 seconds to accelerate from 0 to 100 km/h while its maximum speed is deliberately limited to 250 km/h. Figures like these mean that the Vision SLK 320 CDI Triturbo occupies a special position, even among thoroughbred sports cars. This is particularly true with regard to its fuel consumption. Despite its breathtaking performance, the diesel Roadster makes do with a modest 7.5 litres of fuel per ˜62 mph (100 kilometres) (NEDC combined fuel consumption).

 

The new powerplant in the Vision SL 400 CDI also belongs to the third generation of Mercedes-Benz CDI engines. To create this system, the engineers took the familiar four-litre V8 diesel and enhanced many of its components while also adding state-of-the-art piezo injectors, new turbochargers and an optimised water/charge-air cooling system. Taken together, all of these measures allow the engine to bring forth its power and torque in an even more harmonious fashion. The Vision SL 400 CDI accelerates from zero to ˜62 mph (100 km/h) in 5.8 seconds. Ample justification for this diesel sports car to bear the legendary letters "SL".

 

Comprehensive range

 

Mercedes-Benz offers innovative diesel cars in every category

 

Today's diesel engines are ideally suited to all vehicle categories – as a look at the current range of Mercedes-Benz diesel models confirms. And it is not just their economical fuel consumption and environmental compatibility that make them such a popular choice. In terms of both performance and comfort, diesel engines are firmly established as the equals of petrol powerplants. The current range begins with the 60 kW/82 hp A 160 CDI and extends right up to the new E 420 CDI with its output of 231 kW/314 hp. No less than 20 models on sale in Germany, Austria, the Netherlands and Switzerland already feature a diesel particulate filter as standard while summer 2005 will see 40 Mercedes-Benz models equipped with this technology. In all the other markets, most diesel models are also optionally available with a diesel particulate filter. This means that, worldwide, the Stuttgart-based company will be offering more vehicles with diesel particulate filters than any other manufacturer. Mercedes-Benz has been offering vehicles with diesel particulate filters since autumn 2003, making it the first vehicle manufacturer to combine the diesel particulate filter with EU4 compliance. To date, some 140,000 vehicles equipped with this exhaust technology have been delivered to customers. With effect from autumn this year, Mercedes-Benz authorised workshops will also be offering diesel particulate filters for retrofitting to E and C-Class models.

 

Mercedes can call on a whole range of different systems to minimise exhaust emissions to the required degree. In addition to measures taken inside the engine, such as internal exhaust gas recirculation which is achieved by overlapping the opening times of the intake and exhaust valves, there are a number of exhaust gas aftertreatment methods. These include external exhaust gas recirculation, the oxidising catalytic converter, the NOx storage catalytic converter and the maintenance-free diesel particulate filter. The operating principles of these systems are described below:

 

In the case of external exhaust gas recirculation, the intake and exhaust manifolds are linked by a line. Depending on the operating state, a certain amount of the exhaust gas is added to the intake air. This reduces the combustion temperature and with it the formation of oxides of nitrogen.

The oxidising catalytic converter uses oxygen present in excess air to chemically convert carbon monoxide (CO) and hydrocarbons (HC).

The NOx (oxides of nitrogen) storage catalytic converter first absorbs the oxides of nitrogen and then uses other exhaust-gas components to convert them to harmless nitrogen in short regeneration phases.

Unlike conventional systems, the Mercedes maintenance-free diesel particulate filter does not require any fuel additives. The diesel particulates accumulate in the filter before the residues are burnt and reduced to ash in the regeneration phase through strategic modifications to the fuel-injection, intake-air and charge-pressure parameters.

 

Mercedes-Benz CDI models equipped as standard with a diesel particulate filter***

 

 

*               Diesel particulate filter optional; standard from summer 2005

**             Electronically limited

***            All figures apply to the European market, in some cases to individual countries only; the right to make changes is reserved

****           DPF optional, standard as of model change-over

It all started with the Mercedes-Benz 260 D

 

The success story of Mercedes diesel passenger cars began 70 years ago

 

By the time Mercedes put the world's first diesel passenger car on the road in 1935, the company had already acquired a wealth of experience with "oil engines" as these units were then termed. In April the same year, the Stuttgart-based company was able to celebrate the production of its 10,000th diesel-powered commercial vehicle – a record production landmark at the time. The diesel engine had therefore established itself and was regarded as economical, durable, powerful and robust. But if popular opinion was to be believed, it was completely unsuited for use in a passenger car. Many people might have been prepared to put up with its characteristically throaty, metallic sound, but the vibrations it produced were completely unacceptable. The engineers came to the same conclusion: they fitted the first test engines, 58 kW/80 hp 3.8-litre six-cylinder units, in a number of "Mannheim" test vehicles as early as autumn 1933. Although the standard-production chassis was known for its robustness, they found that the powerplant wore it down remarkably quickly. Their development efforts seemed to be doomed to failure. Could it be that it really was impossible to use a diesel engine in a passenger car?

Of course, "impossible" has never been part of the Mercedes-Benz developers' vocabulary. The engineers pursued their research and came up with a surprising solution. A four-cylinder diesel engine with the same cylinder dimensions and a five-bearing crankshaft behaved in a far more civilised manner. The 2.6-litre engine was configured for a lower power-to-swept-volume ratio, had an output of 33 kW/45 hp, and was fitted in the long Stuttgart 260 chassis. By the middle of 1935, this powerplant had abandoned its remaining bad manners and was ready for series production. Finally, in February 1936, Daimler-Benz presented the Type 260 D at the Berlin motor show in the form of a six-seater Pullman landaulet. One year earlier, the suitability of the diesel engine had already been proven in 13 motor taxis which met with the approval of passengers and drivers alike. From September 1936, the 260 D was offered with a choice of body variants, one of which was the 4/5-seater Cabriolet B. The Mercedes-Benz 260 D was therefore not only the world's first standard-production diesel passenger car, but also the world's first taxi and cabriolet to be powered by a diesel engine. And that, surely, is yet another example of how Mercedes-Benz developers are often well ahead of their time.

 

The Mercedes-Benz 170 D continues the success story

 

The end of World War II marked the beginning of a new era which called for a new, more up-to-date diesel engine capable of continuing the diesel success story. In May 1949, the 170 D and 170 V models – the first Mercedes-Benz passenger cars to be designed after the war – were presented at the Technical Export Fair in Hanover. While the engine design of the petrol-driven 170 V was entirely conventional, the diesel unit in the 170 D was packed with advanced technical features. The charge cycle was now performed by overhead valves, in contrast to the petrol model which still used standing valves. With its output of 28 kW/38 hp at 3200 rpm, the 1.7-litre four-cylinder powerplant offered almost identical performance to its petrol-driven brother yet had the advantage of combining this with extremely favourable fuel consumption. The consummate ease with which it was able to cope with a long service life – even beyond the 200,000 miles mark – also consolidated the reputation for almost indestructible engines which was established by the 260 D. During its first years of production, the fuel situation in the early days of the Federal Republic of Germany also had a positive effect on sales figures. Diesel was in plentiful supply everywhere, whereas petrol remained scarce.

 

A successful combination: the "Ponton" Mercedes and the diesel engine

 

Despite the convincing advantages of the diesel models, they had enjoyed only modest sales success up to this point. All that was to change drastically in 1954 with the introduction of the Mercedes 180 model which was known as the "Ponton Mercedes" (= German for "pontoon"). This first Mercedes-Benz to feature an integral body design caused a major shift in sales figures. Whereas the petrol model attracted 118,234 purchasers, 153,283 opted for the diesel version. In order to continue this success, the first Mercedes with an overhead camshaft was presented in 1958 in the form of the 190 D – the new big brother of the 180 D. The 37 kW/50 hp 190 D soon made a name and a reputation for itself in motoring circles where it

was spoken of as the "lively diesel" – an attribute which had never graced any previous diesel but which clearly indicated the potential of this engine technology. In total, some 235,000 units of the 180 D and 190 D were built.

 

The Mercedes-Benz diesel models also flexed their muscles in the world of motor sport and a 180 D took first place in the diesel class of Italy's world-famous Mille Miglia race in 1955. Karl Kling drove a 190 D to victory in the 1959 Algiers-Cape Town Rally, an extremely punishing haul of 8730 miles. Despite the sand and dust of desert and savannah, Kling was able to record a very impressive � and unbeatable � average speed of 50 mph (80.6 km/h.)

 

More power, more comfort in the "Tail Fin"

 

By the time Daimler-Benz unveiled the successor to the "Ponton Mercedes" at Frankfurt's IAA Motor Show in September 1961, it was perfectly natural that a diesel-powered version should also be on display. The diesel engine in the "Tail Fin" model had already attained the next stage in the evolution of the species and achieved an output of 44 kW/55 hp with a displacement of two litres. The maximum engine speed had by now reached 4200 rpm, a factor which had no negative impact whatsoever on fuel economy or the engine's durability. It was perfectly normal for a 200 D to cover more than 400,000 kilometres in the course of its service life with average fuel consumption of 9.0 l per 100 km (˜23 mpg).

 

Guaranteeing this kind of durability involved subjecting the diesel engines for Mercedes-Benz cars to extremely tough tests. These included the so-called taxi endurance test, which comprised an almost endless succession of full-load operation, switching off and cooling down. Alongside extended runs at full throttle, this was part of the standard programme of endurance tests for any new diesel engine at Mercedes-Benz.

 

Meanwhile, with city traffic becoming ever more dense, the owners could now enjoy a completely stress-free driving experience. Mercedes-Benz could supply cars equipped with optional power steering and automatic transmission. Once again, the company was entering unknown territory, as it was the world's first manufacturer to offer the combination of a diesel engine and an automatic transmission. The addition of this comfort-enhancing feature boosted the popularity of the diesel models once again. In 1965 Daimler-Benz delivered the 500,000th diesel-powered Mercedes to be manufactured since the humble beginnings in 1936. It was an unparalleled triumph for the diesel concept. Sales of the "Tail Fin" model alone amounted to 367,263 units by 1968.

 

The "Stroke Eight": the world's most powerful diesel passenger car

 

The year 1968 also saw the introduction of the legendary Stroke Eight, a series that owes its unusual and unintentional nickname to the abbreviation "/8" � which was originally supposed to refer to the launch year, 1968, as part of the proposed designation 200 D/8 to 250/8. This was deemed necessary to ensure models of the "new generation", as the Stroke Eight was also known, could be clearly distinguished from their predecessors of the same name. In turn, the launch of the 240 D 3.0 was to set a new landmark in 1974. The most powerful standard-production diesel passenger car at the time, it had a displacement of three litres which was shared, for the first time, by five cylinders. Its output of 59 kW/80 hp and 175 Nm gave it remarkable performance. Acceleration from standstill to 100 km/h (˜62 mph) took 19.9 seconds while the top speed was 148 km/h.

 

In the course of its eight-year production lifetime, almost a million units of the diesel powered "Stroke Eight" were sold: 945,206 customers chose one. Never before had a diesel model fired the enthusiasm of so many customers.

 

World premiere for the turbodiesel

 

Launched in 1976 as the successor to the "Stroke Eight", the legendary W 123 was the model that was to finally make the diesel a million-seller. With some 1.4 million units, this model series was, and remains, one of the most successful diesel vehicles ever. But this outstanding sales success was only one of the sensational attributes of the W 123. It was also a trend-setter in terms of technology, too. The engineers at Untertürkheim had appreciated for some time that the future of the diesel lay in greater power – a development objective which could only be attained through turbocharging. This led the Mercedes-Benz engineers to develop a 132 kW/180 hp five-cylinder prototype which was transplanted into the body of a 280 E. Road testing was a resounding success and prompted the decision to build a saloon with a turbodiesel engine.

 

The result was the 300 SD S-Class model, the world's first turbocharged diesel passenger car. As the first premium model to be equipped with a diesel engine, it also offered a high level of luxury and was designed for the US market where Mercedes-Benz also launched the 300 CD at the same time, scoring another world first by combining the 123-series coupé and a diesel engine. In Europe, the turbocharged diesel engine made its debut in the 300 TD Turbodiesel in 1980.

 

1985: The first particulate filter system

 

In 1985, however, Mercedes-Benz engineers also set standards with techniques for reducing particulate emissions. Mercedes-Benz was the first car manufacturer in the world to fit diesel sedans destined for California with particulate filter systems. The experience gained during this programme formed an important basis for the development of innovative filter technologies that are indispensable today.

 

As it is inherent in the operating principle of a diesel engine that its exhaust gases contain little CO2, but a higher proportion of NOx, Daimler-Benz introduced exhaust gas recirculation in 1991. This technology reduces the temperature of the combustion chamber and thus the formation of NOx by about 70 percent. All diesel passenger cars could also be ordered with an optional oxidising catalytic converter.

 

In the same year, the first S-Class diesel was offered in Germany, too. With the W 140-series 300 SD Turbodiesel, which generated an output of 110 kW/150 hp from a displacement of 3.5 litres and made do with 9.7 litres of fuel per 100 km (˜25 mpg), an unstoppable conquest of the luxury segment had begun.

 

CDI technology revolutionises the diesel world

 

The International Automobile Show in Frankfurt ultimately witnessed a quantum leap in the development of diesel engines in September 1997 when Mercedes-Benz presented the C 220 CDI, the company's first model to feature direct injection based on the new common-rail principle. Whereas conventional systems generated the pressure anew for each injection, the new CDI engines operated with a shared pressure reservoir (common rail) which was able to deliver the optimum pressure of 1350 bar regardless of the engine speed. The optimum quantity of diesel fuel for the current operating situation was delivered to the injection nozzles by solenoid valves – as directed by the engine electronics and as needed for each individual combustion chamber. This enabled variable control of the injection process and significantly improved carburetion. The result was lower fuel consumption and few exhaust emissions. The CDI engine from Mercedes-Benz was also surprisingly smooth on the road. That was due to the pilot injection system used by Mercedes-Benz engineers. In this system, a small amount of diesel is injected into the cylinders a few milliseconds before the actual fuel injection. The pilot injection ignites and pre-heats the combustion chambers. Because of this preheating, the increase in pressure and temperature is no longer as sudden when the main injection occurs � the engine runs more quietly.

 

The 92 kW/125 hp four-cylinder engine with four valves per cylinder which powered the C 220 CDI developed an impressive torque of 300 Nm from only 1800 rpm. This represented 30 percent more power than the predecessor model and twice as much torque. In addition, the new engine used ten per cent less fuel. The C 220 CDI thus not only had the highest torque of any diesel car in its displacement class, it also set new standards in the areas of fuel efficiency and pollutant emissions.

 

Moreover, the five-cylinder, 125 kW/170 hp diesel E 270 CDI with 400 Nm and the in-line six-cylinder, 145 kW/197 hp E 320 CDI with 470 Nm likewise grabbed attention with a downright explosion of power. They attained performance levels in no way inferior to those of comparable petrol engines – except as regards fuel consumption, which was about 30 per cent lower. This quantum leap changed the image of the diesel engine for good: instead of being regarded as just remarkably economical, it was suddenly seen as agile, sporty and brimming with power. From the 2000 model year, the highlight of the upper end of the performance scale was the V8 CDI in the S 400 CDI with its output of 184 kW/250 hp and a sensational 560 Nm of torque.

 

Furthermore, CDI technology proved its worth in smaller diesel engines, too. The world’s smallest CDI diesel generates 30 kW/ 41 hp from a displacement of barely 0.8 litres and makes the smart fortwo cdi the best-selling 3-litre car [a car capable of covering 100 km on 3 litres of fuel (˜75 mpg)] in Europe.

 

The maintenance-free particulate filter makes its debut

 

With the launch of the second generation of CDI technology in 2002, performance, economy, comfort and emissions were once again significantly improved. The Mercedes engineers had increased the ignition pressure from 145 to 155 bar and thereby achieved an optimised charge-cycle process which resulted in more pulling power and flexibility. 

 

The combination of the injection pressure (now raised to 1600 bar) and the newly developed seven-hole injection nozzle allowed the fuel to be distributed more finely in the combustion chamber while also resulting in improved carburetion and more even combustion. Mercedes-Benz ventured an important step with respect to the environmental friendliness of the diesel engine in the autumn of 2003 and became the first automaker in the world to introduce diesel passenger cars with EU4-compliant, maintenance-free particulate filters.