New Mercedes C Class: The Testing

Press Release

Field testing of the new C-Class: Around the world 600 times

• Most extensive series of tests in Mercedes-Benz history

• 24 million test kilometres all over the world

• Non-stop testing involving over 900 prototypes and pre-production models

• Systematic "accelerated" endurance test

Learning by testing is one of the maxims the Mercedes engineers live by. Hence they focus on three aspects when developing new models: testing, testing and testing.

In the case of the new C-Class, this principle was applied especially rigorously as the team clocked up over 24 million test kilometres – an astounding feat never before achieved by any other Mercedes model. This distance is akin to circumnavigating the equator 600 times or making 62 trips between the Earth and the moon. A vast amount of time and gruelling test work has gone into achieving a key objective: hallmark Mercedes reliability and long-term quality.

The extensive programme of testing for the new C-Class got underway in summer 2003. At that point, component carriers still concealed parts and components of the new Saloon under the body of the outgoing model. These new components had to prove their worth in special tests under a range of climatic and topographic conditions. Months later the first of a total of 280 prototypes were ready to roll so that, alongside testing of the components for the engines, transmissions, axles, cooling systems and other subassemblies, systematic non-stop testing of the entire vehicle could begin in earnest.

Mercedes test engineers always go to the extreme – the coldest and hottest regions on Earth, the poorest and most dusty roads, the fastest test tracks and the slowest city traffic. These and other exceptional conditions are necessary in order to simulate the stresses and loads a Mercedes-Benz has to withstand over a period of many years within just a few months. During the tests, the end of a car lifetime is reached at a vastly accelerated rate. By way of example, "Heide" torture-track endurance testing, one of the world's toughest series of tests for newly developed cars (also see page 6), involves an acceleration factor of 1 : 150. In other words, 2000 test kilometres are equivalent to 300,000 kilometres of everyday driving by a Mercedes customer.

And there is method behind every test drive. Each kilometre is logged, each test report meticulously evaluated and each potential problem area rigorously analysed and remedied. Hundreds of sensors on board the test cars monitor the technology closely and record temperatures, pressures, voltages and speeds, thus providing a myriad of measured data.

Durability testing of new Mercedes models includes a series of long-distance tests in everyday traffic and on proving grounds, during which the focus is on specific parts, components or functions. Such endurance tests include the "mixed-road test", a standard test for all new Mercedes passenger cars. Based on a precisely defined driving and route profile, each C Class test driver clocked up 150,000 kilometres on a mixture of country roads, motorways and inner-city roads during a one-year period, both during the day and at night. After the hand-built prototypes had completed their stint, the small group of pre-production vehicles completed the lion's share of this world-wide field test from early 2005 onwards. This test included:

• Several full-throttle endurance tests, each covering 50,000 km, at a proving ground in southern Italy;

• Various proving-ground endurance tests, each covering 63,000 km, on all of the heavy-load-inducing track sections at the test centre in Papenburg;

• Several trailer endurance tests, each covering 25,000 km, during which the C Class pulled a 1.9-tonne trailer around the roads of the Swabian mountains in southern Germany;

• Various "accelerated-rate" endurance tests, each covering 81,000 km during a six-month period, including 12,000 km with the maximum trailed load as well as 6000 test kilometres on the Nürburgring racing circuit;

• Electrical endurance tests, each covering 15,000 km, during which test drivers piloted five vehicles and repeatedly tested the electronic systems in the C-Class under real-life conditions.

• A rigorous corrosion endurance test, in which a variety of climate conditions are combined with a typical customer operating profile. This full-vehicle corrosion test simulates approximately 15,000 kilometres of driving under the most gruelling dynamic and climatic conditions.

"World Test": dress rehearsal on three continents

Mercedes test engineers and test drivers are regularly on the road in almost all parts of the world. For instance, engine testing takes place in South Africa, the air conditioning systems are tested in the US state of Arizona and in northern Scandinavia, the car bodies and interiors are put through their paces in Texas, chassis units undergo testing at a proving ground in northern Germany and part of the electrics/electronics testing is carried out in Japan.

But that is not all. The findings and results of all tests are then verified once more in a "World Test". For the new C-Class this was the first part of the final examination before production launch – a dress rehearsal with two fully equipped pre-production models, each of which covered a total of 52,000 km. Once again, this test simulates the stresses and loads experienced during an entire car lifetime.

It all began at the proving ground in northern Germany, with general function testing and 5000 kilometres of driving on merciless gravel tracks. From here, the testing team and the test cars travelled to Finland, to one of the coldest places in Europe, around 150 kilometres north of the Arctic Circle. At temperatures down to minus 40 degrees Celsius and after driving on the heavily snow-covered country roads, the Mercedes engineers paid particular attention to analysing the chassis and body components. In addition, the sub-zero Arctic temperatures provided the perfect opportunity to test the heating and electrical systems in the C-Class. Finally, the Saloons completed a special stop-and-go programme simulating city traffic in Paris, France in order to check the durability of the standard-fit diesel particulate filter in the CDI models.

After three weeks in Finland, the test specialists swapped their fleeced jackets and gloves for T-shirts and sun hats as the Middle East was the next stop-over on the C-Class "World Test" itinerary. Here two extremely hot challenges awaited the cars and drivers: a 12,000-kilometre long-distance test on the tarmac roads and sand tracks of the Arabian Desert and, in between, 5000 kilometres of city testing in heart of a big city where the mercury level rarely falls below 40 degrees Celsius and the traffic is so heavy that walking pace is usually as fast as it gets – an average speed of between seven and eleven km/h. A relentless thermal and wear test involving constant switching between the clutch, accelerator and brake pedals. And yet another extremely tough test for the chassis, air conditioning, engine cooling system and electrics.

But driving was not the expert testers' only task. They also had to stop at regular intervals to complete the checklists that the engineers need in order to be able to assess the quality of the air conditioning, the legibility of the cockpit instruments and the comfort of the seats.

Then came the next extreme test for the new C-Class: 24,000 kilometres in the uplands of Africa and in the Namib Desert. Here, on a daily basis, the test cars negotiated climbs of up to 23 percent and hundreds of bends and hairpin turns in order to reach an altitude of almost 2300 metres. And on the way there they encountered nothing but rocks, stones and dust – road conditions that are rarely experienced by any vehicle. A glance at the test log highlights just what this entails: dozens of tyres and wheels had to be changed during this ultimate test of endurance. And several windscreens, not to mention an exhaust silencer, were broken by flying stones. Apart from this, the test engineers had only good things to report back to Sindelfingen: the major components, chassis, bodies and interiors came through this final torture-track test without any major problems whatsoever.

The final report for this most unique of test marathons runs into several hundred pages. But when all the data sheets, logs and test reports are evaluated, the result is resoundingly clear: the new C-Class passed the "World Test" with flying colours.

Final examination: intensive testing and everyday-driving tests before "Job No. 1"

But this was only the first part of the final examination in the run-up to production launch. Whilst the "World Test" was continuing unabated, the Mercedes engineers sent out another 15 C-Class "Pro" models ("Pro" stands for "Production Test") to undergo a special examination that would take them to six countries within a period of seven months: in Finland, Spain and southern Italy, the main aims were to analyse the body, interior, heating system, climate control and electrics under the influence of icy temperatures and sweltering heat, while in northern Germany, the Middle East and southern Africa, the focus switched to intensive testing of the chassis and its components.

Never before has a new Mercedes model undergone such an extensive additional test programme – and passed it with such top marks.

The same goes for the array of tests which the Mercedes specialists devised specifically for the first factory-produced versions of the new C-Class Saloon. The combination of on-road endurance trials and everyday testing is designed to ensure that the cars have reached their full level of maturity by the time "Job No. 1" – the first C-Class produced for customers – commences on the assembly line.

This final field test also includes the "near-launch road trials" covering a total of around 16 million kilometres, in which DaimlerChrysler employees from Sindelfingen and Bremen test around 450 C-Class pre-production models in normal everyday situations and report back to the development engineers with their findings.