Earlier today, we ran down our list of new green production cars at the 2010 Geneva Motor Show, where press days are now underway. There's one more we might have added to the list: the 2012 Mercedes-Benz E300 Bluetec Hybrid.

At the show today, Mercedes-Benz confirmed that the car "has already successfully entered everyday testing and is scheduled for market launch next year." Daimler chairman Dieter Zesche had confirmed the launch in January, so it's not breaking news.

2011 Mercedes-Benz E300 Bluetec Hybrid

2011 Mercedes-Benz E300 Bluetec Hybrid

2011 Mercedes E250 Bluetec

2011 Mercedes E250 Bluetec

2009 mercedes benz e250 blutec concept 005

2009 mercedes benz e250 blutec concept 005

2009 mercedes benz e250 blutec concept 003

2009 mercedes benz e250 blutec concept 003

Handful of diesel hybrids

Still, it's a fascinating car, the company's first-ever blend of its Bluetec clean-diesel system with the hybrid technology it developed jointly with BMW. When it enters production, the E300 Bluetec Hybrid will be one of only a handful of diesel hybrids offered in the world.

(Late this year, Peugeot will launch its the world's first diesel hybrid as a 2011 model: a 3008 crossover fitted with a mild-hybrid system, which was previewed last year by its 3008 HYbrid4 Concept.)

2.2-liter twin-turbo diesel four

The engine in the Mercedes-Benz E300 Bluetec Hybrid on display at Geneva is a 2.2-liter diesel four with twin turbochargers that puts out an impressive 204 horsepower.

That engine is also used in the 2011 Mercedes-Benz E250 Bluetec, shown at last year's New York Auto Show, which may become the company's first diesel four sold in the U.S. in many years. The company estimated its fuel economy at 28 mpg city, 39 mpg highway.

The Bluetec Hybrid's lithium-ion battery pack and electric motor are similar to those used in the 2010 Mercedes-Benz S400 Hybrid, the company's first, which went on sale last year.

Fuel efficiency of what?

Its 15-kilowatt electric motor sits between the turbodiesel four and the company's 7-speed automatic transmission.  Together, the engine and motor provide peak power of 224 horsepower, with fuel efficiency on the European test cycle of a stunning 57.4 mpg.

That translates to carbon dioxide (CO2) emissions of 109 grams per kilometer, or roughly the level of a standard gasoline compact car. For the E-Class,  a large, heavy midsize luxury sedan, that's an astoundingly low number.

The E300 Bluetec Hybrid also offers electric-only driving for short distances, as well as using the electric motor to boost the engine under acceleration. Like any hybrid, the engine switches off at stops to save fuel.

[Mercedes-Benz]