In addition to facelifting its S550 and S600 models, Mercedes-Benz announced the addition of the S400 Hybrid to its S-Class lineup for 2010 onward. The all-new model is Mercedes-Benz' first ever production hybrid vehicle.

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The internal combustion engine and the hybrid module develop a combined output of 295 horsepower, and a combined maximum torque of 284 pound-feet. The electric motor contributes 20 hp and 118 lb-ft to the powertrain. Fuel economy for the S400 is rated at 19 city, and 26 highway -- yielding a combined fuel economy gain of 38 percent over the S600.

The S400 Hybrid is the first series production hybrid car to be equipped with a lithium-ion battery. During braking the electric motor acts as a generator and is able to recover kinetic energy. The lithium battery is particularly suited to this task. The battery's high energy density means it is small enough to fit in the engine compartment. As such, the trunk capacity and interior dimensions remain unchanged. The car's 7G-TRONIC seven-speed automatic transmission is specially configured for hybrid operation.

"The S400 Hybrid is a major milestone on our road towards emission-free mobility," said CEO Dr. Dieter Zetsche. "In this way the S-Class and the Mercedes-Benz brand are doing important pioneering work for the electrification of the automobile."

Aside from the addition of the hybrid S-class model, another one of the most noticeable changes across the lineup is the addition of daytime LED running lights fitted to the outer edges of the bi-xenon lamp units. The rear end is also accented with a total of 52 distinctively arranged LEDs in the two taillights. Gone are the body-colored strips through the taillamps.

Mercedes-Benz also makes more use of light as a styling element in the interior via the standard ambient lighting, now with a choice between three lighting moods: solar (amber), neutral (white) and polar (ice-blue).

Another noticeable change at the front of the car is a more pronounced arrow-shaped grille, plus a new front bumper with a light-catching contour and a chrome strip below the cooling air intakes. Exhaust tailpipes of all S-Class variants are now visibly integrated into the rear bumper. Mercedes-Benz says its engineers have also implemented specific aerodynamic measures to reduce wind noise.

Camera and radar-based driver assistance systems include Adaptive Highbeam Assist, Lane Keeping Assist and the Pre-Safe brake system linked to the proximity regulating radar, which intervenes autonomously before an impending rear-end collision. Other highlights include the Attention Assist driver drowsiness monitor and Active Body Control with automatic crosswind stabilization.

Engineers also managed to improve the night-vision system with the introduction of Night View Assist PLUS, which is equipped a special pedestrian detection function. The Pre-Safe braking system has also been improved to reduce injuries in unavoidable crashes. Mercedes says the car can apply maximum braking pressure automatically around 0.6 seconds before what is recognized as an unavoidable accident. The system therefore acts as something like an "electronic crumple zone," Mercedes contends.

The multifunction steering wheel of the S-Class has been modified for improved aesthetics and feel. The rim and airbag module are now lined with soft premium leather as standard. The new, flatter airbag module also lends a sporty touch to the multifunction steering wheel.