Mercedes-Benz S-Class BlueHybrid

On the face of it, a hybrid Mercedes-Benz S-Class shouldn't exist. If anyone wants a slightly-more-economical-than-usual luxury car, they should buy a fractionally smaller (but still pretty ritzy in the overall scheme of things) luxury car like an E-Class. Or an S-Class diesel. Actually, if saving the world were really the priority, the vast expense of developing a car like the S-Class hybrid would be much better spent building tidal electricity generators, or just standing in the town square in Stuttgart and handing out free loft insulation.

But Mercedes is obliged to be part of the hybrid revolution. For a start, American luxury-car drivers don't think diesel is a proper fuel for anything smaller than a Peterbilt, whereas the mere existence of a hybrid in the range - albeit a vast and thirsty one - is seen by your average American as sufficient to turn the world's deserts into lush meadows overnight. Never mind, this being Mercedes, the engineers have tackled the hybrid issue with comprehensive diligence. The company is developing two entirely separate hybrid systems. The first is this one, a comparatively mild system that sticks a disc-shaped electric motor in the place where the V6 engine's flywheel would be. Mercedes has another system in the works too, for its SUVs - a full-hybrid that entirely replaces the conventional transmission set-up.

The cost of developing this stuff means it makes sense only if the effort is shared. So the S400's mild hybrid system will also show up on a BMW 7-Series. By the same token, the full-hybrid system is the same as on some of GM's SUVs in the States, and on the forthcoming BMW X6 hybrid.

Despite, or rather because of, the complex technology here, the driving experience is utterly... normal. I drove a prototype, by the way. The real thing will be introduced in the US later this spring, along with a mild range-wide face-lift. Merc calls it the S400 BlueHybrid, even though the engine is a 3.5-litre. Fair play, because it feels a bit more muscular than the S350, thanks to the extra torque that comes from the electric assistance, especially at low revs.

So you've got a car that wafts along with the sort of stately quiet a V6 petrol S-Class normally does. As with an S350, there's enough urge (slightly more in this case) that in normal traffic, or even at a good clip on A-roads, it never seems to be trying that hard. And then you commit to overtaking a bigger line of trucks than usual, or make a spirited attack on a series of uphill bends, and you're reminded thatan S-Class is a pretty hefty lumpof metal and leather; suddenly,the V6 starts to run out of answers and sounds pretty strained.

© Source: topgear
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