BERLIN, GERMANY – For those people who need a bigger, more upscale car, yet would still love to reduce their carbon footprint, Mercedes-Benz will offer another option: the 2009 S400 BlueHybrid, according to

This is a version of the S-Class, a venerable institution in the premium sector: the S350. There is a reworked version of that model’s 279-horsepower, 3.5L gasoline-powered V-6.

Sharing the engine bay is a hybrid system with a 20-hp electric motor. The battery is lithium-ion, making the S400 BlueHybrid the world’s first production car to employ lithium-ion technology, according to Mercedes-Benz.

Like other hybrid systems, this one has a start/stop function and employs braking energy to help recharge the battery pack. A seven-speed automatic transmission has been configured especially for this drivetrain. Compared with a standard S350, carbon dioxide emissions are lower by 21 percent.

The S400 BlueHybrid should be here by next summer, and expect fuel consumption figures to be impressive for a car of this size. Estimates put it at 29 mpg.