What is it?
The new Mercedes-Benz S-class is the best car in the world. At least, that's what its maker wants it to be. And it was a phrase we were inclined to see the rationale behind after our first go in the sumptuous new S-class courtesy of the range-topping S500.
But this S350 BlueTEC has to try and meet that bold aspiration ever more as it is almost certain to be the best-selling S-class. It's all well and good nailing the range-topper, but this bread and butter model is the one that really has to meet its brief.
To help meet the brief, Mercedes has armed the S350 with a 3.0-litre V6 turbodiesel engine. It's the same engine as in its predecessor but armed with more power and torque, lower CO2 and improved economy that are further improved thanks to the S-class's lower weight and improved aerodynamics.
What is it like?
Superb. The best in the world? There's a question. How can that be defined? There are definitely faster, more involving drives, but none that are as comfortable and refined. It's out on its own on as a world beater on those criteria. But we knew that already from the S500 we tested last week, so it's the diesel engine under the S350's bonnet that's up for judging here.
And it's business as usual for the engine; it certainly hasn't got any worse in its switch from old S-class to new. Acceleration is brisk, there's plenty of low-end torque to call on, for the most part it's inaudible from inside the cabin, and it is as buttery smooth and refined as the rest of the car.
Issues? There are a few, although none is a deal-breaker. Throttle response in the cosseting Comfort mode needs to be sharper, particularly when you need a sudden punch for overtaking but this is down to the seven-speed auto' gearbox (another carryover from old S-class to new) as much as anything.
There's also the slightest of gruff notes at start-up, a noise that reappears albeit louder under hard acceleration, something that should be a no-no in a luxury car. It's also not the most willing engine to be revved, but then your average S-class owner is hardly likely to give it the beans, or at least instruct their chauffeur to.
The rest of the dynamic package is typically excellent. The ride quality is superb, it corners flatly and handles with confidence-inspiring stability rather than any great level of driver involvement.
The ride could probably be made even better still if Mercedes' Magic Body Control (an incredible piece of engineering that can make speed bumps feel like they aren't even there) were to be offered, but it's only available on V8-equipped S-classes. Shame, but S-classes without it hardly feel like a poor relation.
The interior comfort is beyond reproach, the overall functionality and design less so. The twin front screens are a bit ugly, and the optional pair you can have in the back can only be operated by a fiddly remote or a smartphone app when you'd think they'd be touchscreen as standard in this iPad era. It can also be quite hard to find the button or menu for the command you actually want (skipping tracks on an album for instance).
Still, if all this winds you up you can always slip into the back seat, recline almost flat and have a hot stone-effect massage.
Should I buy one?
If you are a luxury car customer who wants the most comfortable and refined car out there then the S-class is for you. A Range Rover has a much greater sense of occasion, a Jaguar XJ is much more involving to drive, but just as those two cars nail their briefs for those traits the S-class nails its own for its grown-up manners and role as a businessman's express.
But there is the slight nagging doubt that it hasn't moved the game on as much as the new Range Rover did when it arrived. It feels like more of the same, and in parts, particularly the interior, it is a bit derivative.
Maybe we're nitpicking, as this is the one car you'd pick out of any class for a 1000-mile drive, or indeed passenger ride. It's just when the aspiration is to be "the best car in the world", you expect that extra five per cent, be it in a revolutionary new engine, gearbox or particularly an interior more in tune with the Apple generation, that will allow it to top any class in addition to its own.
Mercedes S350 BlueTEC L SE Line
Price £65,650; 0-62mph 6.8sec; Top speed 155mph; Economy 50.4mpg; CO2 148g/km; Kerb weight 1975kg; Engine V6, 2987cc, turbodiesel; Power 254bhp at 3600rpm; Torque 457lb ft at 1600-2400rpm; Gearbox 7spd automatic