From October 2003, Mercedes-Benz will be the first car manufacturer in the world, it claims, to offer the combination of EU 4 exhaust emission standard and diesel particulate filter for its high-selling diesel passenger cars.

The combination of EU 4 and diesel particulate filter will initially be available for the C-class and E-class models with four-cylinder CDI engines. To date, 85% of C-class and about half of all E-class diesel customers have opted for the 200 and 220 CDI engines. At the beginning of next year, the six-cylinder CDI engines in the E-class and S-class will follow suit.

The particulate filter system developed by Mercedes-Benz operates without additives and, depending on the individual use profile and thus with no fixed change interval, remains efficient over a very high mileage.

"This makes us the first manufacturer to offer a system which both adheres to the EU 4 limits and almost completely eliminates particulate emissions - and does so with our most important diesel engines, the one which dominate fleet business", said Mercedes car group head Jürgen Hubbert.

In Germany Mercedes-Benz is offering the combination of EU 4 and diesel particulate filter for the four-cylinder CDI models for €580 (including VAT tax). When registering such a vehicle for the first time, Mercedes customers in Germany, the United Kingdom, Belgium, Sweden and the Netherlands will enjoy tax benefits which effectively reduce the additional cost by a significant amount, or even balance it out completely.

Service life, everyday practicality and fuel consumption were key criteria in the development of the particulate filter system. For this reason, a filter system that was dependent on additives was simply out of the question. Investigations show that, although such fuel additives improve the burn-off of particles that have accumulated in the filter, the ash remaining in the filter channels is not renewable and, after a high mileage, this ash can block the filter. As a result, the exhaust gas back-pressure increases and, consequently, so does the fuel consumption and, in turn, the C02 emissions, whilst the performance of the engine drops continuously.

With the Mercedes-Benz particulate filter system, it is possible to achieve high mileages without the need for additional service measures. The filter is regenerated by adjusting, in accordance with requirements, various engine-control functions, such as fuel injection, intake-air throttle, exhaust-gas recirculation and boost-pressure control. In this way, it is possible to increase the temperature of the exhaust gas and the particles accumulated in the filter are burned off. Test results show that, after a high mileage, the residual ash is up to 75% less than that produced by additive-dependent filter systems. Sulphur-free fuels and specially developed engine oils will mean that these diesel particulate filters have an even longer service life.

Due to the new particulate filter and its new CDI engines - which have common-rail direct injection, four-valve technology, exhaust-gas recirculation and oxidation catalytic converters - Mercedes-Benz has now succeeded in reducing particulate emissions by about 87% since 1995. From 2005, the EU 4 limits also stipulate a further 84% reduction in gaseous emissions.

Added Hubbert: "The simultaneous reduction in exhaust-gas emissions and in fuel consumption is one of our primary objectives. However, in order to exploit fully the great future potential, we need not only state-of-the-art engine technology, but also both clean fuels and innovative fuels, such as 'Biotrol', the fuel recently introduced by us for diesel engines; this is manufactured from renewable raw materials and is clean-burning."