AS THE luxury flagship of one of motoring’s founding automotive brands, Mercedes-Benz says the S-class has done more for road users than any other model.

It also claims that, with 2.7 million sedan and coupe versions sold, the car that brought us the occupant safety cell and the airbag has been a benchmark for luxury cars for 55 years, as well as the top-seller for the past 40.

Representing the pinnacle of Mercedes’ engineering prowess, the S-class has a big reputation to live up to – none more so than the ninth-generation example, which faces increased competition from less expensive but highly accomplished rivals like BMW’s recently upgraded 7 Series, Audi’s new A8, Jaguar’s XJ and the Lexus LS430.

So what does the $269,900 S500L – the first of three all-new W221 S-class sedan variants to go on sale in Australia in 2006 - bring to a stagnant luxury car market in Australia in the company’s 120th anniversary year?

First, there’s a much rounder body shape that appears more elegant, more organic and more compact than its W220 predecessor released in late 1998 – a model that was drastically downsized following criticisms that its W140 forebear (the infamous "Schwein Klasse") was simply too big, too extravagant and too anti-social.

The fact the model is actually larger in every key dimension than the W220 is testament to its cohesive exterior design, which shrinks cleverly around its 70mm-longer wheelbase yet provides a couple of inches more legroom, almost as much extra shoulder room and, less obviously, a fraction more headroom.

Helping to disguise its larger dimensions (it’s slightly heavier, too) are design features like a more sloping bootlid, a rounder roofline, a rear-end that’s no longer vertical but inclines forward and headlights that are no longer scalloped but almost triangulated.

It’s a modern, logical progression of the S-class shape that surprises only with its inclusion of wildly flared wheelarches that some may consider more appropriate for a sports coupe than a large luxury sedan.

As such, there’s noticeably more stretching room inside, where higher-quality materials, more modern switchgear and a beautifully crafted real woodgrain and chrome highlight deliver an undeniably greater sense of occasion than before – even if the dashboard lacks the design pizzazz of the A8 and takes on a 7 Series-style Spartan-ness about it.

This is partly a result of its employment, for the first time in S-class, of an i-Drive-style controller for the COMAND cockpit management and data system, which lacks the more intuitive touch-screen offered by Lexus but compensates via well-executed laptop-style TFT colour instrument and central monitor displays.

Negating the need for anything but an analogue clock and manual audio volume and climate controls on the dash, the system operates everything from the rear blind, lighting and auto-locking settings to the climate-control, satellite-navigation, telephone and trip computer systems.

Speaking of the 7 Series, Mercedes-Benz corrects criticism that the W220’s bootlid design is a direct copy of the controversial, "taxi-style" item found on BMW’s current luxury flagship (which was apparently necessitated by the dominant US market’s requirement for carting at least two full-size golf bags around) by pointing out the fact that its million-dollar Maybach limousine had one first.

Sadly, the rear seat still lacks the added load-carrying practicality of a split-folding function because it’s incompatible with the power-adjustable outboard rear seats that are now standard in long-wheelbase versions. There is, however, a full-size spare wheel.

It’s also easy to criticise the curious fact that Mercedes’ largest sedan is even more of a four-seater, because the centre rear seat cushion is harder and its passenger is still forced to sit on both the seatbelt clasp and the side bolsters for the two more accommodating outboard buckets - even if there is more legroom.

But of course Mercedes counters by insisting few S-class drivers – particularly those of the 130mm-longer LWB versions – carry four full-size passengers.

While the nicely stitched leather-look Artico dash looks and feels great in the S500L (the only variant available at launch), we’re yet to sight the dashboard in lesser S-classes. Similarly, we’re unable to substantiate claims the short-wheelbase W221 is more of a driver’s car.

But, in long-wheelbase guise at least, it’s certain all the top-shelf Benz hallmarks are here. As you’d expect from what’s claimed to be the quietest S-class ever, its cabin remains near-silent at all speeds.

With the exception of some road roar on course-chip surfaces – especially in the rear and especially in 235/55 R17 Michelin-shod versions – the new S-class approaches Lexus LS430 levels of cabin quietness, and irons out all manner of road irregularities with impeccable finesse.

Our S500L was a model of stability on the open road, where it was in its element as a super-comfortable, luxuriously-appointed high-speed tourer from which to watch the world waft by.

Proving that not even an S-class can be all cars to all people, however, on twisting, uneven surfaces that are so typical in country Australia, the new model was unable to hide its significant bulk as its big body keeled over into bends, its superbly-weighted steering began to feel too slowly geared and kicked back on many occasions, and its plush leather seats revealed a distinct lack of lateral bolstering.

That said, none of its rivals would have fared much better in such circumstances and, for those prepared to pay for the likes of sportier seats, there’s an extensive (and expensive!) options list – and a host of AMG-tuned performance variants to come.

But there’s no doubting the S500L’s credentials as a modern masterpiece of automotive excess. The new 5.5-litre V8 makes the previous S500’s 225kW 5.0-litre V8 seem positively anaemic by offering a rich band of useable torque right from idle (peaking at a muscular 530Nm) and delivering no less than 285kW of power.

Combined with a pleasing V8 soundtrack and Benz’s seven-speed auto, it was never found wanting in any situation, and returned under 12L/100km fuel consumption on the highway, rising to a still-respectable 13L/100km in the hills.

Mercedes claims average consumption of 11.7L/100km and this seems not only achievable but is identical to its three-valve predecessor, which delivered 60kW and 70Nm less performance.

As in 7 Series, gone is a conventional gearshifter, replaced by a right-hand side steering wheel stalk via which one selects drive, reverse or park. Actual gear-shifting, if required, is accomplished by pushing buttons on the back of the steering wheel (left side to change down, right for up) – all of which sounds complicated but becomes second-nature after a short, enthusiastic drive.

GoAuto found the best compromise was to select fifth gear, which negated the overly tall-geared transmission to provide some engine braking and response – as well as to automatically downchange - when required. Top gear sees 100km/h come up at around just 1500rpm.

A Manual/Standard/Comfort switch, which links the transmission and semi-active air suspension systems, allows the S500L driver to select between plush-riding suspension (comfort), automatically-adaptive (standard) and firmer-riding, manual-shift (Manual) modes.

Of course, the W221’s technical advances – let alone the carryover list of safety, comfort and convenience features offered in a model line that opens not far short of a cool $200,000 - are far too extensive to detail here.

Surprise-and-delight features include quad windscreen washers, a bootlid-mounted umbrella holder and ambient interior lighting, while the standard door and bootlid-closing assist feature is welcome on the S500.

All models get PARKTRONIC parking assistance, a voice-controlled telephone, TV, six-DVD sound system and satellite-navigation as standard, as well as a sunroof, tyre pressure monitor and active bi-Xenon headlights with washers and cornering lights.

But one of the most significant additions is the option of Night View Assist ($4090 in S350, $3590 in the S500s and standard on S600L), which uses near-infrared technology to present an image of the road and any obstacles on a black and white screen that replaces the instruments. It penetrates as far as the Xenon high beams do and is highly effective.

The latest-generation Distronic Plus adaptive cruise control system, which benefits by the ability to operate under 30km/h and therefore even in stop-start traffic, will be available within months, following Mercedes’ application to change legislation to allow road users to use the 24Ghz radar frequency.

And then there’s Active Body Control (optional at $8290 in S500/L, standard in S600L), which Mercedes says is the world’s highest performing such system and reduces body movement by 60 per cent.

ABC supersedes the 7 Series’ clever Dynamic Drive active roll-bar function by replacing stabiliser bars with automatically adjusting the air spring platforms – on top of the standard air suspension’s ability to adjust damping and ride height to suit conditions (30mm lower above 80km/h).

After a 450km drive in the new S500L it’s clear that S500L easily justifies is $6000 higher pricetag over its W220 predecessor (which, in turn, came at a vastly reduced price compared to its forebear) via improvements such as noise and vibration suppressing technology from Maybach, including acoustic foil-insulated glass and a patented floor structure.

Throw in push-button sports/touring chassis adjustment, a torque-laden yet frugal new big-bore V8 and a larger, quieter and more comfortable cabin with improved safety features and equipment, and there’s no reason to doubt Benz’s claim this is also the most advanced, most dynamic S-class ever.

Whether it’s good enough to remain at the top of the luxury limousine tree only the customer will decide.