Mercedes, GM Developing Diesel Hybrids

Peugeot is still on track to launch the world's first diesel-hybrid vehicle late this year. Its 3008 HYbrid4 Concept is a thinly disguised version of a crossover fitted with a mild-hybrid system that will go into production late this year as a 2011 model.

Now other manufacturers are joining the party. Mercedes-Benz plans to launch its first hybrid-electric car with a diesel engine in 2011, and even GM has engineering prototypes on test tracks to help it figure out the best combination of electric-drive components with the fuel-saving engines.

The new technology will be launched in Europe, where diesels are common; whether it will come to the U.S. is unclear.

Mercedes E300 Hybrid for 2012

Now Daimler chairman Dieter Zesche has confirmed the launch of the 2012 Mercedes-Benz E300 Hybrid, using a 2.2-liter diesel four with twin turbochargers, in late 2011. That's the same engine used in the E250 Bluetec shown at last year's New York Auto Show, which may go on sale for 2011 in the U.S. as the company's first diesel four in years.

The lithium-ion battery pack and electric motor in the E300 are similar to those used in the 2010 Mercedes-Benz S400 Hybrid, the company's first, which went on sale last year. It adds a 15-kW electric motor between its 275-horsepower, 3.5-liter V6 engine and a 7-speed automatic transmission.

Both cars are mild hybrids, meaning the electric motor adds power to that of the combustion engine, as well as restarting it from stops. But they are not capable of running in all-electric mode, like such full hybrids as the Toyota Prius.

Mercedes-Benz also showed the 2009 Mercedes-Benz Vision S500 Plug-In Hybrid Concept at last fall's Frankfurt Auto Show, another hybrid adaptation with a larger battery pack that can be recharged by plugging it into wall current for up to 18 miles of all-electric range. That car is expected to go on sale in 2012 as the top model in a totally redesigned S-Class range of full-size luxury sedans.

40-mpg E-Class

The EPA rates the S400 Hybrid's gas mileage at 19 miles per gallon city, 24 mpg highway, but many drivers have achieved more than 25 mpg is real-world use. The E300 Hybrid is projected to return compact-car fuel economy of 40 mpg or more.

The diesel hybrid system is also expected to be used in the company's M, GL, and R-Class sport utility and crossover lines built in Alabama, along with the GLK compact crossover. It's not at all clear, however, that the diesel hybrid models will be sold in the U.S.

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