Mercedes-Benz has released further details on its first production model equipped with a hybrid drive system, the S400 BlueHYBRID that will go on sale in Europe in June 2009 with 
Quite importantly (and unless someone beats the Germans to it), the S400 BlueHYBIRD will be the first series-production model to be equipped with a lithium-ion battery. The advantages over conventional nickel/metal hydride batteries include a higher energy density and better electrical efficiency, together with more compact dimensions and a lower weight.
What’s more important to consumers is that the battery pack is installed in the engine compartment, where it replaces the conventional starter battery. This means that the interior space and boot capacity of the S400 remain unchanged. Additionally, thanks to its compact dimensions and modular design, the additional weight of the overall hybrid system including the comprehensive safety systems is only 75 kg or 165 lbs.
As with most hybrids today, when the vehicle is braked the electric motor acts as a generator, and is able to recover braking energy which is then stored in lithium-ion battery pack and made available when required. The hybrid module also has a start/stop function, which switches the engine off when the vehicle is at a standstill- for example at traffic lights. When it's time to move on, the electric motor restarts the main power unit.
According to Merc’s official figures, the S400 BlueHYBRID accelerates from standstill to 100 km/h (62 mph) in 7.2 sec, and reaches an electronically governed top speed of 250 km/h or 155 mph. More importantly, the S 400 BlueHYBRID betters the average fuel consumption figure of the conventionally powered S350 by up to 2.2 lt /100 km, at 7.9 lt /100 km (29.8 MPG US) and CO2 emissions by 21 percent at 190 gr /km.
