What is it?
This is the Mercedes S 400 BlueHybrid, the company's first production hybrid. Mercedes has developed the drivetrain technology in a joint venture with BMW, which plans to use it to underpin the similarly conceived 7-Series ActiveHybrid.
Visually, little distinguishes the Mercedes S 400 BlueHYBRID from the car it's based on, the three-year old S 350.
There are no aerodynamic tweaks or changes in ride height, only subtle BlueHybrid badges serve to give the game away.
What's it like?
The S 400 uses a lightly reworked version of Merc's existing 3.5-litre V6 petrol engine, with a new cylinder head, lightweight pistons and a reprofiled crank, although it does without the direct injection that Merc uses in other applications.
Output increases by just 7bhp over the S 350 at 279bhp, with torque remaining the same at 258lb ft.
The clever bit is the disc-shaped three-phase AC electric motor mounted within the front of the gearbox housing, and providing additional thrust when required, output swelling to 299bhp and 284lb ft, with drive channelled to the rear wheels via the standard seven-speed automatic gearbox.