Mercedes-Benz is ready to launch their new hybrid system, and S-Class will be the first model to receive it. A new M256 straight six engine will have an electric motor directly attached to its crankshaft.
The motor can act as an alternator and a starter which allow the engine to fire up less than a second. It can help the S-Class to supply additional horsepower and at the same time generate electric through regenerative braking too. Unlike current hybrid system, the engine cannot be turned off, and both systems will work all time. It is also said Mercedes is working on 4-cylinder engine with less advanced belt-driven starter/ generator for their future models.
(via AutoCar UK)