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2010 Mercedes-Benz S400 Hybrid

The Ultimate Sedan For The Energy Conscious Aristocrat


2010 Mercedes-Benz S400 Hybrid

Without the big "Hybrid" decals on this press-fleet mobile you'd never know this S-Class Mercedes boasts a gas/electric powertrain


Mercedes-Benz builds big, powerful, über engineered sedans: Autobahn burners for heads of state and captains of industry, not fuel sippers for penny pinchers.

But now the company behind the three-pointed star is using some of its world-famous engineering prowess to make its flagship S-class easier on a tank of unleaded. And unlike almost every hybrid on the market, the Mercedes-Benz S400 Hybrid isn't more expensive because it's a hybrid — it's actually the cheapest S-class sedan available. Moreover it's eligible for an $1,150 tax credit.

Pricing, Performance and Powertrain

Starting at $87,950 the S400 Hybrid is $3,650 cheaper than the 382hp V-8 powered S550 and it offers a nice fuel savings too: 19 city/26 highway for the hybrid versus 15 city/23 highway for the conventional powertrain. Under the big Benz's hood resides a DOHC 3.5-liter V-6 worth 275hp and 258 lb.ft. of torque. But what's more interesting is the .9 kilowatt-hour lithium ion battery pack, roughly the same dimensions as a conventional automobile battery, that sits in the right rear of engine compartment. This compact battery provides the juice for the disc-shaped 20hp three-phase AC electric motor between the engine and car's seven-speed automatic transmission. The S400 isn't a full hybrid, it's a mild hybrid so it can't run solely on electric power. The electric motor assists during stops and starts and under acceleration. Like GM's mild hybrid cars and trucks, the S400 Hybrid's V-6 engine shuts off when the car isn't moving and thus uses no fuel. The air conditioning compressor and the power assist for the steering are electric, so their function is never interrupted. Step on the gas and the S will hit 60 mph in 7 seconds and cover the quarter-mile in 15.5 with the electric motor chipping in to provide a seamless performance boost. When it's time to slow down, the electric motor goes into regenerative braking mode sending power back to the Li-ion battery pack. When the speed drops below 10 mph the V-6 engine is switched off. If the driver applies only light pressure to the pedal, the electric motor/generator slows the car, step into the pedal harder and the S400's friction brakes kick in. In reverse, the hybrid on-off engine switching is disabled altogether.

The Eyes Have It

The driver can monitor the S400's hybrid system with a monitor subtly embedded in the speedometer, rather than on a separate screen mounted elsewhere on the dash. The display show's a bird's eye view of the car and simplified icons of the gas engine, electric motor and the Li-ion battery pack. Green arrows point toward the motor and battery when electricity is being generated, red arrows lead away from the motor and battery when power is being used. The display also shows the battery's charge as a precentage. Beyond the hybrid display, a small Hybrid badge on the trunk lid and what some testers have described as a somewhat numb brake pedal feel, there is nothing to alert your fellow country club members that the S class you're driving is easier on resources than the 382hp V-8 powered S550 or the 510hp V-12 S600. From behind the wheel the S is a blend of restrained Teutonic luxury car style and impressive technology. Premium leather upholstery is accented by hand-polished Burl Walnut trim and a matching Burl Walnut wheel is available at extra cost. While many cars are equipped with dashboard mounted displays, M-B's COMAND system allows the driver and front passenger to view two different images on the same screen. For example, while the driver is using the radio or navigation system, the front passenger can enjoy a DVD video. When the splitscreen is active, the driver still has full access to the COMAND system's functions, while the front passenger uses the included remote control and wireless headphones to enjoy their own entertainment choice. Further upping the high-tech ante the S can also be outfitted with a “Night View Assist” feature that allows the driver to more easily spot pedestrians, animals, etc. on the road ahead.

Hybrids For The Well Heeled

Does the Mercedes-Benz S400 Hybrid represent the future of hybrid powertrains in high-powered sedans of the rich and famous? Clearly this is a good way to have your caviar and eat it too: power on tap without a huge fuel mileage penalty. It's also a nice way to get a tidy little tax break, something the financially astute are always on the lookout for. Paired with one of Mercedes-Benz's clean new BLUETEC diesels, a project that Mercedes-Benz already has well underway, one has to wonder if the days of 300-plus horsepower and 30-plus mpg are far off.

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