Although it's based on the S350 platform, Mercedes' new S400 Hybrid is a completely different animal.
For one thing, it's the first Mercedes sedan to receive a hybrid drivetrain. For another, it's the first production Mercedes to utilize a lithium-ion battery pack.
Also found in laptop computers, lithium-ion batteries deliver a lot of punch for their size. But overheating has been a nagging problem, as anyone who has experienced a self-immolating laptop will tell you. The new fully electric Nissan Leaf also uses lithium-ion - as do other electric vehicles - but its designers have laminated the battery itself for better heat dissipation. Battery technology continues to be a major challenge for all manufacturers.
At any rate, the Mercedes S400 battery pack feeds a thin electric motor located between the engine and transmission, and the entire drivetrain develops some 295 horsepower at 6,000 rpm.
This gives the 2,050-kilogram S400 somewhat leisurely acceleration, especially from a dead start, but combined fuel economy in the 8.0 L/100 km/h neighbourhood, which is better than the S350 it's based on. Mercedes is claiming a 0-to-100 km/h time of just over seven seconds for the S400h, but that's more than I could manage; several non-official runs netted me acceleration times in the nine- to 10-second range. And anyway, this is a hybrid car - how quickly it gets up to freeway speed should be irrelevant, shouldn't it?
This is also one of the so-called "mild" hybrids. It cannot propel itself on battery power alone, in other words, and the electric motor acts as a starter and a supplement to the engine when more power is needed. Very similar to Honda's approach, in other words.
The S400 also shuts off when the vehicle comes to a stop and then restarts itself when you take your foot off the brake pedal. This aspect of the system works a treat; the transition back and forth between starting and shutting off is virtually imperceptible.
A cute little graphic on the instrument cluster also lets you know the state of charge for the battery pack and, like virtually all hybrids, the S400h has a regenerative braking system that recharges the batteries when you decelerate or hit the brakes.
The whole setup works nicely, but has been done before, and can't really be described as cutting-edge technology.
As far as the gasoline engine goes, it's a 3.5-litre V-6 unit taken from the S350 and given the once-over. Among other things, it features a redesigned cylinder head and an Atkinson-cycle valve arrangement, which basically means that the intake valves stay open a smidgeon longer to take maximum advantage of the combustion process. Other manufacturers, such as Ford and Toyota, use this system as well.
Transmission is Mercedes' ubiquitous seven-speed, which is used throughout the company's lineup. One minor note here: the S400 requires premium gasoline, which kind of negates any fuel cost savings you might gain from the hybrid system.
You could, in all fairness, ask the question: what is the point of this car? At $105,000-plus to start, it's not cheap, and the people that can afford it aren't likely to be concerned with the price of gas or how reasonable the fuel consumption is.
Hybrid drivetrain or no, this is still a big, top of the line luxury sedan and gives up nothing when it comes to creature comforts and mod-cons.
Speaking of which, the S400 has a full whack of features designed to pamper its occupants. Standard equipment includes full leather interior, heated/ventilated front buckets, electronic parking brake, power rear window sunshade, intelligent cruise control, steering wheel shift paddles, Bluetooth connectivity and the Mercedes Attention Assist system - which monitors the driver, taking note of his/her driving, and evaluating it, with a view to providing a warning at the onset of fatigue or drowsiness - and on and on.
It also comes with one of my favourite goodies: a heated steering wheel, which, in this kind of weather, is huge. My tester also had the optional Premium package ($6,100), which, among other things, includes self-massaging front seats and a back-up camera.
I like the latter feature, but find the former almost creepy. I don't want any automobile kneading my backside, thank you very much.
Virtually all functions for the S400 are accessed via a stationary mouse and rotary dial located on the centre console (very similar to that found in some Lexus products).
Maybe it's because the majority of cars I drive these days have much more conventional controls and ergonomics, but I find this setup counter-intuitive and laborious. To pre-set a radio station, for example, takes four separate steps and, indeed, the S400 displays a warning to you, right off the bat, when you start the car: do not allow this system to divert your attention from traffic and road conditions, it admonishes. A good idea in theory, but kind of impractical.
That probably applies to the S400 Hybrid overall. It's a lovely car, no question, with impeccable road manners, over-the-top comfort features and unassailable credentials. But aside from the fact that it runs cleaner (apparently), it seems to be a statement as much as it is a luxury sedan. Then again, what Mercedes isn't?
2010 MERCEDES-BENZ S400 HYBRID
Type: Full-size luxury sedan
Base Price: $105,900; as tested: $112,000
Engine: 3.5 litre V-6/electric motor
Horsepower/Torque: 295 hp/284 lb-ft
Transmission: Seven-speed automatic
Fuel Economy (litres/100 km): 11.0 city/7.7 highway; premium gas
Alternatives: Lexus LS600h, BMW ActiveHybrid7