2010 Mercedes-Benz S400 Hybrid review: 2010 Mercedes-Benz S400 Hybrid

2010 Mercedes-Benz S400 Hybrid

Wayne Cunningham

Wayne Cunningham

Managing Editor / Roadshow

Wayne Cunningham reviews cars and writes about automotive technology for CNET's Roadshow. Prior to the automotive beat, he covered spyware, Web building technologies, and computer hardware. He began covering technology and the Web in 1994 as an editor of The Net magazine.

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2010 Mercedes-Benz S400 Hybrid

The Good

Maps in the 2010 Mercedes-Benz S400 Hybrid show fully rendered 3D urban centers. The Harman Kardon stereo delivers excellent audio quality. Blind spot detection warns against unsafe lane changes. Massage seats are icing on the cake.

The Bad

The hybrid system's start-stop feature runs a little rough. The suspension and power train Sport mode buttons are separate, and placed far apart.

The Bottom Line

The 2010 Mercedes-Benz S400 Hybrid bundles a wide array of very useful tech, and its hybrid system helps the car avoid the gas guzzler tax.

With night vision, adaptive cruise control, a sweet-sounding Harman Kardon audio system, and over-the-top features such as massage seats, the 2010 Mercedes-Benz S400 Hybrid is everything an S-class should be: one of the most comfortable cars on the road with a host of tech amenities. At the same time, it is also the least expensive S-class, both in initial price and running costs.

All of the cabin tech and driver assistance features in our test car are available across the S-class line, and we will get to those in a minute. First, however, we must discuss the novelty of an S-class hybrid.

Hybrid power
Unlike the Lexus LS 600h, in which Lexus merely chose to add a big hybrid drive system to the LS' existing V-8, giving it tremendous power, Mercedes-Benz downsized the S-class engine, replacing the base level 5.5-liter V-8 with an Atkinson cycle 3.5-liter V-6.

A 20-horsepower electric motor assists that engine. The power doesn't sound like much, but the electric motor's more important function, assisting launches, benefits from its 118 pound-feet of torque, adding to the engine's 258 pound-feet. However, as a mild hybrid, this electric motor doesn't drive the car by itself; it merely boosts the engine.

Mercedes-Benz packs a lithium ion battery pack into the engine compartment.

Mercedes-Benz says that this combination gives the S400 Hybrid the power of a V-8, but that doesn't feel quite right. It is a big car, and it feels sluggish off the line. According to Mercedes-Benz's own figures, the S400 Hybrid gets to 60 mph in 7.2 seconds, whereas the V-8 S550 makes it in 5.4.

A button on the console toggles the throttle response between Comfort and Sport modes, the latter giving it a little more of a performance edge, but we found that it took a lot of gas pedal input to get anything like a quick take-off. The S400 Hybrid just doesn't move as effortlessly as the S550.

Mercedes-Benz kept the hybrid system's weight under control by using a 120-volt lithium ion battery pack--the first use of this type of battery chemistry in a major production hybrid. Because of the high power density, the battery is small enough that Mercedes-Benz packaged it under the hood, so it doesn't take up trunk or cabin space.

You can view the battery status from a graphic in the S400 Hybrid's speedometer, which shows the power flow from engine to battery to wheels. Likewise, the standard tachometer reveals this hybrid system's most useful feature: start-stop technology.

Stop the car at a light or in traffic, and the engine shuts down, saving gas. As soon as you lift off the brake, the engine kicks in again.

This animation on the speedometer shows power flow from engine to battery to rear wheels.

We found no problem with the functionality of this technology. For instance, the power was always ready when we wanted to go. But instead of a seamless push forward, we could feel the engine start up each time, which detracts a little from the car's overall luxury feel. However, this start-stop technology is easy to live with, and doesn't impinge nearly as much as in some other mild hybrids.

Although the driving feel isn't as good as we would have hoped, the hybrid system pays off in that the S400 Hybrid escapes the gas guzzler tax, which hits all of its siblings, and gets about 4 mpg better than the S550.

EPA gas mileage for the S400 Hybrid is 19 mpg city and 26 mpg highway. We achieved close to 21 mpg during our testing. As for emissions, the hybrid system gets it a Super Ultra Low Emission Vehicle rating from the California Air Resources Board.

A little sport
The faults we ascribe to this hybrid system show themselves only during urban driving; out on the open road, the S400 Hybrid feels no different from any other S-class. With the air suspension in Comfort mode, the car delivered an extremely smooth ride, insulating us from the outside world.

The big, plush seats contributed to the ride quality. With the Premium package, these seats incorporated massage technology, letting us choose between four different modes for the manner in which it would knead our backs. Mercedes-Benz includes dynamic seat bolstering with these seats, as well, which makes the bolsters inflate to counteract butt movement during cornering.

You can fine-tune the seats for lumbar support, and choose from four massage modes.

That latter technology might seem superfluous in a luxury cruiser like the S400 Hybrid, but this car offers some minor sport capability. Pressing the aforementioned throttle response button, we put the power train in Sport mode, and for good measure activated the Sport Suspension mode, using its separate button next to the LCD. The placement of these two Sport mode buttons, in very different places, is one of our minor annoyances with the car.

With all Sport modes on, the S400 Hybrid delivered very sports car-like flat rotation during hard cornering, the suspension working to counteract body roll. But the engine and electric motor couldn't put enough twist down for us to properly power out of the corners.

Like most recent Mercedes-Benzes, the S400 Hybrid uses a stalk mounted on the steering column as the shifter for the seven-speed automatic transmission. This car also gets paddle shifters on the steering wheel spokes for sequential manual gear changes, which let us coax a little more power from it.

Gadgets galore
A new feature of the navigation system helped out during our mountain driving escapades. Along with the usual 2D and bird's-eye maps, Mercedes-Benz incorporated a new 3D map into the navigation system, showing topographical details. This map not only gave us advanced warning of curves in the road, but made rises and descents clear, as well.

Similar to new 3D maps in Audi and BMW models, the S400 Hybrid shows maps of major urban areas in incredible detail. Driving through downtown San Francisco, the map rendered every building, adding textures to a few notable landmarks.

The S400 Hybrid lets you take virtual tours of cities with its 3D maps.

Mercedes-Benz also followed Acura's example by incorporating Zagat restaurant listings into the navigation system's points of interest database. Searching for an eatery in the Zagat category, the system not only showed ratings for food, decor, and service, but also included comments to give a more complete idea of what each restaurant is like.

The maps show traffic information, and the navigation system uses this data to dynamically calculate routes. For freeway travel, the route guidance graphics include an indication of which lane the car needs to be in for each junction or off-ramp. Our only disappointment with this navigation system was that it doesn't give much advanced warning for each maneuver, which is problematic when you are sailing down the freeway and 70 mph.

The navigation system stores its maps on a hard drive, and Mercedes-Benz reserves a portion of that storage space for music, letting you rip CDs in the car. We were also pleased to find solid iPod integration in the car, with a full view of the iPod's music library on the LCD.

Audio sources for the S400 Hybrid's stereo abound.

Music plays through a Harman Kardon audio system, using a 600-watt amp and 15 speakers. The results are excellent, with some of the clearest and well-balanced audio we've heard in a car. Bass is never overpowering, and the highs come through with rich clarity, making every sound distinct.

A fine Bluetooth phone system was also present in our car, offering full phone book capabilities.

Beyond that fairly typical cabin tech content, Mercedes-Benz loads the S400 Hybrid with all manner of driver assistance technologies. As we've seen in previous Mercedes-Benz models, radar gives the car adaptive cruise control. We were very impressed that when a car ahead of us stopped on the highway to make a left turn, the S400 Hybrid brought itself to a complete halt. When the road ahead was clear, our car accelerated to our preset speed, although there was a significant wait for it to hit the gas.

We found blind spot detection very useful on this car, as people seemed to drive perpetually off our left or right quarters. This system shows a red icon in the side view mirror if a car is in the next lane, and makes it blink if you hit the turn signal. However, if the car is visible in the S400 Hybrid's side mirror, the warning won't light up; it only turns on when other cars are truly in the blind spot.

Lane Keeping Assist is another new technology on the S400 Hybrid. It monitors the lane lines, giving a warning if you cross over without signaling. Its warning consists of a very light, intermittent rumble of the steering wheel. But this warning is so light that it doesn't seem like it would wake a dozing driver. We would like to see Mercedes-Benz increase the intensity.

Night vision lets you see more than you can with the naked eye.

Driving at night with the night vision system on is a very interesting experience, as it changes the speedometer, which is really just an animation on an LCD, to an enhanced view of the road ahead. It lets you quickly glance down and see further ahead than you can with the naked eye. We've found it works best on very dark roads with no other cars around, as headlights and taillights tend to blow out the image.

In sum
The 2010 Mercedes-Benz S400 Hybrid is a high-tech marvel, incorporating innovative and ground-breaking technologies to assist drivers. The blind spot detection and adaptive cruise control both contribute to the driving experience. Standard cabin tech features, comprised of navigation, Bluetooth phone, and the stereo, are all first rate. We particularly like the audio quality of the car's Harman Kardon sound system.

We could wish for a full hybrid system in this car, but the existing system makes the V-6 engine a viable choice to drive the big S-class. In turn, that choice avoids the gas guzzler tax and gets the car reasonable gas mileage. The air suspension enhances the performance, making the car a luxury cruiser and giving it some cornering capability.

Spec box

Model2010 Mercedes-Benz S-class
TrimS400 Hybrid
PowertrainMild gas-electric hybrid 3.5-liter V-6
EPA fuel economy19 mpg city/26 mpg highway
Observed fuel economy20.8 mpg
NavigationStandard hard drive-based navigation with traffic
Bluetooth phone supportStandard
Disc playerMP3 compatible six disc changer
MP3 player supportiPod
Other digital audioOnboard hard drive, auxiliary input, satellite radio
Audio systemHarman Kardon 600 watt 15 speaker
Driver aidsNight vision, adaptive headlights, adaptive cruise control, blind spot warning, lane departure warning, rear-view camera, automatic high beams, rain-sensing windshield wipers, driver attention monitor
Base price$87,950
Price as tested$111,090

2010 Mercedes-Benz S400 Hybrid

Score Breakdown

Cabin tech 9Performance tech 8Design 8


See full specs Available Engine HybridBody style Sedan