We've seen Mercedes petrol-electric hybrids before. Can a diesel-electric S-Class make the grade? Jonathan Crouch reports.
Ten Second Review
The Mercedes-Benz S300 BlueTEC Hybrid is a rare swing and miss from Mercedes. It's neither smooth enough nor economical enough in the real world to earn a solid recommendation. It's still an extremely good car, but we come to expect virtual perfection when shopping for S-Classes.
Like it or not, the motoring landscape is changing. The manual gearbox is fast becoming a museum piece, electronic control systems are getting ever smarter and hybrid vehicles are no longer the preserve of granola-munchers wringing their hands over the plight of polar bears. The broadening relevance and attraction of hybrid cars has even spread to a section of the market that might have once seemed wholly impervious to the requirement to be seen as clean and green - the luxury limousine. Mercedes-Benz tends not to do things by halves when it commits to a technology. Thus you can not only buy an S500 Plug-In Hybrid, you can also choose from an S400 petrol-electric hybrid and, maybe the most interesting of the lot, the S300 BlueTEC diesel-electric hybrid. Will people really buy an S-Class that's got a tiny 2.1-litre four-cylinder diesel engine plumbed under that vast bonnet? Mercedes thinks so and is bullish about this car's prospects in the UK market.
First things first. Do you get that typical S-Class magic carpet smoothness? Yes and no. You certainly do when the car is running in electric mode, but when the 201bhp diesel engine cuts back in, you'll feel some vibes through the steering column and when worked, it lacks the outright smoothness of the six-cylinder diesel. Let's put these comments into perspective though. It's astonishingly smooth for what it is, a relatively small-capacity diesel tasked with moving a huge car. The seven-speed automatic transmission is smoother than a Dean Martin drinks order and when given everything, the S300 Hybrid will get to 62mph in a crisp 7.6 seconds and nudge 150mph if you can reserve yourself a quiet stretch of autobahn, so it's unlikely you'll find it lacking go. There's the torque of the electric motor that feels like you're being cupped by a huge hand and urged forwards and the weight of that battery pack in the boot keeps the centre of gravity low, making the S300 feel a lot more nimble than any car that weighs over two tonnes has any right to. If Mercedes could only find a way to take the edge off start-up clatter on cold mornings, you could almost forget this one drank from the black pump.
Design and Build
The styling of this latest S-Class is probably more evolutionary than any previous all-new model, with the pronounced wheelarch bulges and coupe-like roofline carried over from the previous W221 generation. Look a bit closer, however, and you'll see the additional shape in the flanks courtesy of slashing swage lines, there's the more upright front grille and the swept-in tail, much in the style of the CLS four-door coupe. The lighting system deserves more than a passing mention. More than 100 years after the introduction of electric lighting in motor vehicles, Mercedes-Benz is making a complete switch to LED technology - the new S-Class is the first vehicle in the world whose interior and exterior do without a single light bulb. Out of consideration for any road users behind, the intensity of the brake lights is reduced at night or while waiting at traffic lights which is no bad thing. Some Mercedes models in the recent past have had antisocially bright tail lights. Almost 500 LEDs illuminate the road, the vehicle, the interior and the boot. Depending on equipment, these include headlamps with up to 56 LEDs, tail lights each with up to 35 LEDs (plus 4 for the rear fog lamp) and no fewer than 300 LEDs in the interior, including the ambient lighting. Both the standard and long wheelbase models wear their bulk with a light touch, and there's plenty of room inside the beautifully-finished cabin. You can even specify the "First Class Rear" where the front console on the transmission tunnel is visually continued to the rear. It's equipped with innovative thermo-cup holders which use Peltier technology to cool or warm drinks over a longer period of time. Like an aircraft seat, the centre console is available with two tables which can be folded in or out using one hand. The twin front screens aren't the prettiest and the optional pair you can have in the back can only be operated by a tedious remote control or a smartphone app.
Market and Model
If you were thinking of a diesel-electric S-Class because you might save a few bob, Mercedes have played a rather cruel trick on you. The S300 BlueTEC Hybrid is initially only offered in long-wheelbase guise and in top-spec AMG Line trim which means that you're going to be asked for just over £72,000 before pen meets paper. A short-wheelbase model is set to join the line up, but you're still going to have to pay around £1,500 more for this car than the equivalent conventional S-Class model, the S350 BlueTEC V6 diesel. Is it worth it? That's a tough one to answer. This car's certainly not shy of standard kit. It gets AirMATIC air suspension with Adaptive Damping System, the 7G-Tronic Plus 7-speed automatic transmission with steering wheel gear shift paddles and an LED Intelligent Light System. Eighteen-inch alloys come as standard while the interior features leather upholstery, dark brown eucalyptus wood trim and the excellent COMAND Online infotainment system. There are also Frontbass speakers, using hollow chassis members to punch up the stereo's bass response. The AMG Line version also gets AMG body styling, comprising front apron, rear apron and side skirts, as well as 19" alloy wheels in 5-twin-spoke design with perforated brake discs. The interior features black poplar wood trim with a wood- and leather-trimmed multi-function steering wheel, brushed stainless steel sports pedals and velour floor mats with 'AMG' lettering.
Cost of Ownership
On paper, it's hard to grumble about the S300 BlueTEC Hybrid's numbers. Mercedes quotes 61.4mpg on the combined cycle and emission of 120g/km. Now we know that it's worth taking claimed economy figures with a pinch of salt but most road testers have returned rather perplexed with the S300 BlueTEC Hybrid, their fuel consumption averaging somewhere around 35mpg. This is something of an issue, because that's pretty much what you'll average with the S350 BlueTEC diesel, which is a quicker, cheaper and far smoother car to drive. Couple that with the rather puzzling way that this car is being marketed and the S300 BlueTEC Hybrid neither stacks up as a bargain buy nor as a car that will be the standout performer in terms of pence per mile. It's a fair bet that its residual values will stand up a bit better than a non-hybrid diesel, but if you were expecting this car to change the game for good, you might be disappointed.
The Mercedes-Benz S300 BlueTEC Hybrid promises much and delivers a strong performance. The problem is, strong isn't what we expect from an S-Class. We expect strong from an Audi A8. S-Class buyers demand brilliance, overwhelming, unfeasible superiority. And you're not buying that with this car. The Audi A8 2.0 TFSI Hybrid and the BMW ActiveHybrid 7 both manage to make the Mercedes feel a tiny bit uncouth at times, which is something you certainly wouldn't expect. Pair this hybrid tech with the larger V6 engine and you'd have a model that would be a guaranteed winner. It would have the power and refinement you'd expect and while you'd still need to mind the gap between the claimed and actual economy figures, that would be a car we could get behind. As it stands, the S300 BlueTEC Hybrid is the least convincing variant in a standout S-Class line up. Mercedes will build a fantastic diesel-electric S-Class. Unfortunately this car isn't it. That said, we don't think you'll have to wait too long.