Mercedes S400 BlueHybrid

The Mercedes Benz S400 Hybrid is the world’s first mass produced car with a lithium ion battery. It’s the first Mercedes with a hybrid drive. And, with a price tag just below $90,000, it’s an ultra-niche vehicle. The S400 Hybrid arrived in US showrooms in August 2009.

Its competition in the nascent luxury green vehicle market is the $90,000 BMW X6 Hybrid (although it's an SUV); the $109,000 all-electric Tesla Roadster (although it's a two-seater); the $87,000 four-door Fisker Karma plug-in hybrid (not yet out); and the $104,000 Lexus LS 600h L—a V8 hybrid averaging 21 miles to the gallon. Lexus annually sells about 1,000 units of the LS 600h L.

We achieved 29.3 miles per gallon in the Mercedes S400 Hybrid, over a 150-mile mixed driving course though Southern Germany.

The offical EPA mileage number for the Benz S400 are 19 in the city and 26 on the highway. HybridCars.com did our own mileage test of this big luxury sedan on the roads of Southern Germany. Our drive loop took us from Stuttgart—the home of Mercedes Benz—to the town of Buel and back, a round trip of approximately 150 miles. The route was evenly comprised of high-speed driving on the Autobahn—where we ran at, ahem, greater than 100 mph—as well as moderately paced rural roads, and narrow streets through smaller hamlets. We achieved an impressive 29.3 miles per gallon—not bad for a car that weighs almost 5,000 pounds. (By the way, the V6 of the S400 is plenty strong for the Autobahn.)

With much stricter speed limits in the US, it’s reasonable that fuel economy results will be even better. But saving fuel and money is not the first concern for buyers of this car. The buyer of the S400 hybrid is probably just as interested in pairing the Mercedes three-pointed star emblem with a hybrid badge, to demonstrate a combined interest in luxury, refinement, and green status. Mercedes claims that the S400 is the “CO2 champion in the luxury class,” emitting a relatively low 186 grams of carbon per kilometer.

As the hybrid version of the Benz flagship S-Class sedan, the S400 is powered by a mild hybrid system with a 3.5-liter V6 gas engine. The hybrid system allows Mercedes to maintain its high-power profile, while using a V6 instead of a V8 or V12. The electric-gas combo provides a total output of 295 horsepower, channeled through a seven-speed automatic transmission. Benz is particularly proud of what it refers to as “compact” batter technology. Engineers made this hybrid system as well-packaged and light as possible. (Mercedes-Benz was able to fit the entire pack into the same space, at the right-hand base of the windshield, that previously housed the car’s standard lead-acid 12-Volt starter battery.) The S400 weighs only about 120 pounds more than the standard S-Class.

Driving Manners

The S400 drives much smaller than it is. Cutting through the tight twisties of Germany’s Black Forest, this hybrid cornered flatly and with confidence. It is as nimble and agile as its gas-powered counterpart. Stability comes from Active Body Control, an active suspension that continually adapts the suspension tuning to the current driving situation. The S400 features Torque Vectoring Brake, as well as Crosswind Stabilization, both enhancing the sure-footedness of the car. Other high-tech advancements include a pre-collision system, adaptive high beam assist, lane keep assist, and radar-based cruise control.

The cabin of the car is as plush as the standard S-Class. It shares all the same luxury features including a new split-view driver interface, which allows the front passenger to watch a movie without distracting the driver. There’s also a “Night View Assist” feature that detects pedestrians on the road ahead. The only interior difference is the S400’s hybrid gauge showing the flow of power between engine, battery, and regenerative braking.

The S400 shares the look of the S-Class. Signs of its recent facelift include a more aero grille, revised LED lighting at the front and back, and new mirrors, tailpipes, and wheels. The Mercedes Benz S400 hybrid is a luxurious, fuel-efficient saloon with lots of driving appeal. With its steep purchase price, it’s obviously not for everyone—but it is one more option for uncompromising affluent buyers seeking a slightly greener ride.

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