Mercedes Hybrid coming to USA

The 2009 S400 BlueHYBRID will be Mercedes-Benz’ first hybrid passenger car and also the first mass-production hybrid with a lithium-ion battery that’s been specially developed for automotive use. The S Class hybrid will go sale in Europe in June 2009 and be available in the U.S. three months later.

Based on the S350, The S400 BlueHYBRID has a 3.5-liter V-6 gasoline engine mated to a 7G-TRONIC seven-speed automatic transmission with reprogrammed management software for the hybrid application. It also has a new auxiliary oil pump for transmission lubrication even when the engine is switched off.

A compact, disc-shaped electric motor is installed in the torque converter housing between the engine and transmission. This three-phase, 120 volt AC external rotor magneto motor provides 20 horsepower and a starting torque of 118 lbs-ft (160 newton meters). When added to the 279 horsepower of the 3498 cc engine, a maximum of 299 horsepower is available. With a total of 284 lbs-ft (385 newton meters) starting torque, the S400 BlueHYBRID accelerates spritely from zero to 62 mph (100 km/h) in 7.2 seconds when the accelerator is punched. It has an electronically governed top speed of 155 mph (250 km/h).

The electric motor is both a starter for the start/stop function and generator for regenerative braking. The engine is switched off when rolling to a stop at less than 9 mph (15 km/hr) and is almost imperceptibly restarted when the brake pedal is released or the accelerator is pressed. Intelligent control logic detects when turning or parking so the start/stop function is temporarily deactivated.

Selecting “R" on the transmission activates the maneuvering mode to prevent the start/stop function from switching off the engine at short, frequent intervals. The motor/generator dampens torsional vibrations in the drivetrain to reduce interior noise and vibration. Electric power steering and electric air conditioning are used.

The S400 BlueHYBRID’s motor acts as a generator when braking to keep the Li-ion battery charged. Besides saving fuel, regenerative braking saves brake wear and tear since brakes are only activated when the driver applies heavy pressure to the pedal. Otherwise, braking is provided by engine compression and regenerative braking alone.

The car’s lithium-ion battery offers higher energy density and greater efficiency compared to nickel-metal-hydride (NiMH) batteries, which means more compact dimensions and lower weight. Thus, the battery is located in the engine compartment and replaces the conventional starter battery, leaving the interior and trunk space unchanged. The 120 volt Li-on battery not only stores energy for the electric motor, but via a transformer provides normal 12 volt vehicle electric power. A 12-volt lead/acid battery is installed in the trunk. The entire system, including comprehensive safety systems, weighs 165 pounds.

Mercedes-Benz says the S400 BlueHYBRID is the world's most economical luxury sedan that uses a gasoline engine. Compared to the S350, fuel economy is improved by up to 2.2 liters per 100 kilometers for an overall rating of 7.9 liter/100 km (30 mpg). Overall CO2 emissions are reduced by 21 percent to just 190 grams per kilometer, for the world's lowest CO2 emissions in this vehicle and performance class.