Mercedes-Benz S-class S 350 CDI L review, road test

On to the biggest change – the engine. It’s the same 2,987cc turbocharged diesel V6 you’ll find in the ML 350 CDI and GL 350 CDI, and it’s also paired to the same seven-speed 7G-Tronic torque-converter automatic gearbox.

The power output of 255bhp is pretty much par for the course amongst the current crop of luxury 3.0-litre V6 diesels, although the 63.22kgm torque figure is class best, if only just. Incidentally, that’s also 45bhp and 13.3kgm more than the old S 350 CDI. How does it feel on the road? In a word – serene. Apart from a brief thrum on start-up and the slightest suggestion of a purr should you approach the somewhat modest 4,200rpm redline, the level of refinement is almost eerie. This just doesn’t sound like a diesel engine.

Updated 3.0 V6 diesel makes 45bhp and 13.3kgm more than in the old S.

Set off, and you don’t get any sort of maniacal shove, there’s no judder from the gearbox and there’s certainly no hint of anything as bourgeois as turbo lag. There are just two settings for the engine and gearbox – Eco and Sport; the former also gets paired with engine stop-start by default, which can then be turned off independently. We found, however, that for most cases, Sport is the better choice, even if it’s the chauffeur at the wheel. The responses are better and the gearshifts, though quicker, aren’t any more jolting or apparent in the cabin. Eco works well if you want to save fuel, sure, but when setting off from a standstill, there’s an annoying trough in the power delivery that can create a mild lurch, which is not something you want interrupting your business nap in the back seat. Overall, however, power delivery comes via a superbly linear and creamy-smooth surge that just builds and builds all the way to the redline.