What is it?
It’s the UK’s most popular S-class model by far, scooping up more than 80 per cent of sales. And Mercedes-Benz is now giving buyers further reason to choose the S 350 CDI, or S 350 Bluetec, to give it its new name.
Changes to the 3.0-litre common-rail diesel engine – including improved injection efficiency, added turbocharger boost pressure and reduced compression ratio – boost power by 22bhp at 254bhp. Torque rises by 59lb ft to 457lb ft, developed at 1600rpm, as before.
What’s it like?
The upshot is added off-the-line performance, even more impressive mid-range shove, relaxed cruising attributes and a level of mechanical refinement that encroaches on that of petrol S-class models.
Mercedes has also fitted its latest urea injection system. Concentrated within the catalytic converter, it turns up to 80 per cent of nitrogen oxides expelled by the engine into harmless nitrogen and water. A 25.7-litre tank for the urea solution is mounted in the spare wheel well and needs retopping every 15,500 miles.
The engine changes are backed by a revised seven-speed automatic gearbox with stop-start. It helps make the S350 Bluetec achieve a combined 41.5mpg and a CO2 rating of 177g/km. It also fires off shifts in a more determined way than before.