Start-stop function: the engine switches off automatically when idling
In the case of the petrol engines, Mercedes engineers have achieved NEDC fuel savings of up to 0.4 litres per 100 kilometres with a newly developed ECO start-stop function. From autumn 2008 this system will be available for the high-volume models A 150 and A 170 on request. It automatically switches off the engine when the driver shifts the manual transmission to neutral at a low speed while applying the brakes. If the conditions for engine switch-off are met, the driver is informed by a special display in the instrument cluster.
Within fractions of a second, and almost noiselessly, the engine is restarted as soon as the clutch is operated or the brake released. This rapid and comfortable engine start is a major advantage of the ECO start-stop function versus other systems of this kind. To this end Mercedes-Benz uses a starter generator which is linked to the crankshaft via the drive belt. As a result the engine starts much more rapidly and quietly than with the conventional starter. During a journey the starter generator feeds electrical power to the onboard network of the A-Class.
Economy: nine percent lower fuel consumption in city traffic
With the ECO start-stop function the NEDC fuel consumption is reduced by a further 6.5 percent or so. The A 150 BlueEFFICIENCY (70 kW/95 hp) absolves a measured test journey with a fuel consumption of 5.8 litres per 100 kilometres, which corresponds to 139 grams of carbon dioxide per kilometre.
Even greater advantages can be achieved in normal road traffic, as the results of extensive practical trials have confirmed: Mercedes employees tested the system in 175 test cars, covering a total of around 1.2 million kilometres. Roughly half of this enormous mileage was covered in city traffic, where the new ECO start-stop function enabled fuel savings of up to nine percent to be achieved.
Ecology: the A-Class is the first compact car with an environmental certificate
Practical trials such as this are of immense importance to Mercedes-Benz when it comes to evaluating new technologies. The environmental compatibility of vehicles is not only assessed on the basis of standardised emissions and fuel consumption measurement, but also taking into account the entire vehicle lifecycle – from production and many years of operation to eventual recycling and disposal. An analysis of more than 40,000 individual processes provides an overall picture and enables the development work to be objectively assessed.
This form of environmental audit is the basis of the environmental certificate according to the stringent international ISO standard 14062 (Design For Environment), which Mercedes-Benz is the world’s only automobile brand to have received. This certificate also applies to the new-generation A-Class, confirming the considerable advances made in the field of environmental protection. An analysis over a vehicle mileage of 150,000 kilometres shows that CO2 emissions are around seven percent below the figure for the preceding model (W168) of 2004, for example. Nitrogen oxide emissions have been reduced by no less than 13 percent.
Even better results are achieved by the A 150 BlueEFFICIENCY with the ECO start-stop function. Thanks to this new technology, carbon dioxide emissions over the entire lifecycle are reduced by a further five percent, which means that the environmental audit shows a remarkable reduction in CO2 emissions by more than twelve percent compared to the preceding model.
Aspects other than favourable fuel consumption and low exhaust emissions are also important for the environmental certificate. For example the recycling concept of a vehicle: the A-Class already meets the EU regulation coming into force from 2015, which prescribes a recycling rate of 95 percent. Plastic components with a total weight of 30.8 kilograms can be produced from high-grade recyclates – twice the figure achieved for the preceding model.
The A-Class also demonstrates its environmentally compatible concept by the use of renewable raw materials. Mercedes-Benz has various components of the compact car produced with the use of flax, olive stones, cotton, coconut fibre, wood veneers and abaca fibres. The weight of these components has increased by one third versus the preceding model. Detailed information about environmental audits may be found in a Mercedes-Benz brochure, which is available on the internet at www.media.daimler.com .