Mercedes-Benz is launching its first passenger car model equipped with a hybrid drive system in summer 2009—the S 400 BlueHYBRID.

The BlueHYBRID is based on the S 350, and features an extensively modified drive train. This encompasses a further development of the 3.5-L V6 engine, an additional magneto-electric motor, seven-speed automatic transmission specially configured for the hybrid module and a high-voltage lithium-ion battery.

The compact hybrid module is a disc-shaped electric motor that acts as a starter and generator to save fuel and increase driving enjoyment.

This is partly due to the booster effect of the electric motor, as it backs up the engine with additional torque during the high-consumption acceleration phase.

The hybrid module also features a start/stop function, which switches the engine off when the vehicle is at a standstill, at traffic lights for example. When it's time to start moving again, the electric motor restarts the main power unit in barely noticeable fashion. Emissions are also minimized during the starting phase.

When the vehicle is braked, the electric motor acts as a generator and is able to recover braking energy by a process known as recuperation. The electric motor supplements the braking effect of the engine and the wheel brakes to deliver a smoothly progressive braking action. The recuperated energy is stored in a lithium-ion battery in the engine compartment, and made available when required.

The centerpiece of the hybrid drive system is the new high-voltage lithium-ion battery, which was specially developed for automotive use and is the first such unit worldwide to be introduced in a series-production vehicle.

The lithium-ion battery not only stores energy for the electric motor, but is also connected to the 12-volt onboard network via the transformer to supply power to other standard consumers such as the headlamps and comfort features.