Based on the S350 platform, Mercedes’ S400h hybrid was introduced in 2010 and was a completely different animal. It was the first Mercedes sedan to receive a hybrid drivetrain and the first to utilize a lithium-ion battery pack. This latter item was – and is – controversial. Under some circumstances, this variety of battery has been known to overheat and occasionally burst into flame. No such reports for this model, however.
A thin electric motor located between the engine and transmission supplemented a 3.5 litre V6, and the entire drivetrain developed some 295 horsepower at 6000 rpm. Combined fuel economy was in the 8.0 L/100 km/h neighbourhood, which was superior to the S350 it was based on. Interestingly, the Lexus 600h, the S400h closest rival, was thriftier in town, but thirstier on the highway.
The S400h was also a so-called “mild” hybrid. In other words, it couldn’t propel itself on battery power alone, and the electric motor acted as a starter as well as supplying more power when needed. It also shut the powertrain off when the vehicle came to a stop and re-started itself when you took your foot off the brake pedal……pretty standard fare these days. Like virtually all hybrids, the S400h had a regenerative braking system that recharged the batteries when you decelerated and/or hit the brakes.
The gasoline engine was a 3.5 litre V6 unit taken from the S350, and suitably modified. Among other things, it featured 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. While this is good for fuel economy, it takes away from performance. Transmission was Mercedes’ ubiquitous seven speed, and the S400h required premium grade gasoline. A road-burner it was not.
Being a Mercedes, it came with a full magilla of features designed to pamper its occupants. Standard equipment included full leather interior, heated steering wheel, heated/ventilated front buckets, electronic parking brake, power rear window sunshade, intelligent cruise control, steering wheel shift paddles, bluetooth connectivity, and on and on.
It also came with Mercedes’ Attention Assist system, which monitors the driver, taking note of his/her driving behaviour, evaluating it, and providing a warning at the onset of fatigue or drowsiness. The optional Premium package included self-massaging front seats and a back-up camera.
Virtually all functions for the S400h were accessed via a stationary mouse and rotary dial located on the centre console (very similar to that found in some Lexus products). Some drivers found this set-up to be counter-intuitive and laborious. To pre-set a radio station, for example, took four separate steps, and interestingly, the S400h displayed a warning to the driver to not allow the system to divert his/her attention from traffic and road conditions as soon as they turned on the ignition.
No safety recalls for this one….either from Transport Canada or the US National Highway and Traffic Safety Administration. The latter organization, however, does have a few technical service bulletins for this year of the S class…..15 in all. For example, there are engine cooling issues with virtually all variations of this model, a complaint about a “cracking” noise when the height adjustment is activated on the front seats, steering wheel “vibrations”, and a complaint about Mercedes’ Parktronic parking assist program.
Consumer Reports doesn’t have much to say about the S400h, but does like the S-class in general. Says C.R.: “the S-class has always been stately and luxurious”, and “the ride is still first class, but handling is fairly sporty as well.”
Marketing researcher, J.D. Power, meanwhile, rates the S-class highly when it comes to things like powertrain mechanical quality and body and interior quality design, but is less enthusiastic about its powertrain design. It gets a “better than most” rating for overall quality. Comments from owners: “excellent phone and navigation system”, “really high quality seats”, and “temperature control sometimes a little off.”
The S400h was not one of the company’s high-volume models. From a base price of just under $110,000 in 2010, it has dropped in value by at least half. Depending upon equipment level, prices for this luxury hybrid start in the low-$50,000 neighbourhood, going up to the mid-$50,000s.
2010 Mercedes S400h
Original Base Price: $105,900; Black Book: $54,250; Red Book: $51,425
Engine: 3.5 litre V6/electric motor w. lithium-ion battery pack
Horsepower/Torque: 295 hp / 284 ft. lb;
Transmission: Eight-speed automatic
Fuel Economy (litres/100 km): 11.0 city/7.7 hwy. Premium gas
Alternatives: Lexus LS600h, BMW ActiveHybrid7