MUCH has happened in the four years since Mercedes-Benz unveiled the current, ninth-generation S-class.

Besides the global economic fallout, a myriad of fresh competitors have arisen for the Mercedes flagship, from the redesigned BMW 7 Series and Mk4 Lexus LS to Porsche’s mightily impressive Panamera.

Times, it appears, have never been tougher for the evergreen S-class.

So it was with some scepticism that we approached the W221 series facelift, just launched in Australia.

Now, our experience with the earlier iteration S500 back in 2006 left us in little doubt that the three-pointed star had re-ascended to the top of the fat-cat category, for its combination of comfort, ability, quality and class. This Benz felt like a Mercedes should.

But that ballistic Panamera is a towering achievement while the F01 7 Series is a sublimely athletic luxury express. Surely both relegate the S-class to a distant third?

Well, the good news is that latest version – a mild facelift with a few more features here and there – is still at least as good as any of its competitors, no matter how much younger they are.

Far from looking aged inside or out, the fundamental rightness of the design still shines through, imbuing a timeless beauty to it that – we must say – is missing in some of the brand’s other sedans.

Too bad the distinctive body-coloured tail-light strip has vanished though, while the 200-plus LEDs lighting the limo up like a runaway Christmas tree at night might be a bit much for some tastes.

Stepping inside, the improved seats seem at least as comfy as the sumptuous old ones, there is an abundance of space in the regular wheelbase model (let alone the stretched LWB version), and nothing looks cheap or shoddy. Again, no other Benz can approach the big one for quality and feel – or quality feel for that matter.

We’ve always been especially fond of the piano-style key console area, with the well-machined action of the switches and controls, as well as the gentle flow of the stitched-leather binnacle, so we’re glad nothing much has changed here. Nothing really needed to.

Mercedes’ upgraded TFT window now has a split-screen display so the driver sees navigation info while the passenger – looking at exactly the same area – can watch a DVD or TV. Super clever, like those 1960s glossy postcards with pics that appeared to move when you altered the viewing angle.

This is a personal thing, but the steering wheel is a bit on the fugly side, but other than that, there is nothing really to fault inside the latest S-class in their most standard guises.

And even the briefest of turns of said tiller will reveal that Mercedes still makes one of the best driving behemoths out there, with well-judged steering weight and feel, backed up by smooth and flowing handling and roadholding capabilities.

However, not all S-classes are created equally, as a stint at the wheel of the S350 V6 petrol and S500 V8 petrol, as well as a brief squirt in the intriguing S350 V6 CDI turbo-diesel, revealed – even though all three versions shared variations of the same, superb 7G-Tronic seven-speed automatic transmission.

We would choose the 3.0-litre S350 CDI (173kW/540Nm) over the 200kW/350Nm 3.5-litre S350 petrol in a heartbeat, because the 3.5-litre premium unleaded user simply lacks the performance to match the majesty of what Mercedes is trying to convey in the S-class.

Yes, the S350 petrol powerplant is commendably smooth, but you must forever prod that accelerator pedal for meaningful motivation, and then keep on doing so when you need to overtake or simply make a quick getaway at speed. This is the weak link in the S-class chain.

In contrast, the S350 diesel is a muscular delight, providing heady take-off performance (after a slight hesitation) followed by a steady stream of oomph well into three-figure road speeds. This combined with quite remarkable refinement and near-dead silence as well as measurably better fuel economy, means that going diesel is a no-brainer. C’mon wealthy Australia, let’s do something for the environment and cede to the CDI.

Yet the silky punch of the S500 is a compelling story in itself. This petrol V8 glides along the road with regal disregard for stuff like hills or bad roads or traffic snarls. Cocooned in that classy cabin, and with a handy 285kW/530Nm well of revvy goodness to draw from, the Mercedes is a great ground-speed coverer, as well as a relaxing and lush driving experience.

If it wasn’t for the fact that there is a well-equipped four-cylinder C-class worth of price difference between the S350 CDI and S500 then we would probably stuff the trees and butterflies and plonk our collective bottom into the latter. This car feels like the quintessential S-class experience.

Which, by definition, is traditionally the ultimate luxury limousine experience this side of a Roller or Bentley.

Familiarity and age have not faded the charms of the latest S-class one bit.

The mega Merc is still a massively impressive technology and safety fest that emphatically delivers rather than disappoints, while delighting with its many details. An example of how naturally it does this is the automatic radar cruise control system, which is the most intuitive we have ever experienced, to the point where the car almost behaved like it was on auto pilot.

The prices may be prohibitive (thanks, punitive federal government taxes), but – as an enjoyable day swanning along in the facelifted S-class revealed – Mercedes should not have too much to fear from the newer generation of competitors out there.

The W221 S-class is still great after all these years.