Mercedes-Benz S Class

On the move, there's still nothing quite like the serenity and elegance of an S-Class and the cruising experience on offer here remains a particularly special one, even by the opulent standards of the boardroom segment.

Exemplary ride quality remains this model's key calling card, even better this time round thanks to the way the AIRMATIC air springs interact with the heavily re-engineered 'MRA' 'Modular Rear Architecture' platform.

The super-slippery 0.22Cd drag factor ensures that highway refinement is class-leading too: which is where you can make use of the segment's best developed 'Level 2' autonomous driving tech - Mercedes' Active Distance Assist DISTRONIC' system, which works with 'Active Steering Assist' to basically look after steering, throttle and braking duties for you at cruising speeds.

The car's been engineered for 'Level 3' and 'Level 4' tech too - basically driving itself without you - for whenever legislation permits that to happen. For now though, you might be happy to enjoy driving it yourself, even in town, where this Mercedes eases through urban jams on a different plane to the motoring masses.

Beneath the bonnet, all S-Class variants bound for our market feature in-line six cylinder 3.0-litre power, the options beginning with the 286hp S350d diesel rear-driven variant we tried.

The same engine features with 330hp mated to 4MATIC AWD in the S400d.

Or there's a 435hp petrol powerplant in the S500 4MATIC, which benefits from the brand's current 'EQ Boost' mild hybrid tech.

That AMG-derived petrol unit also forms the basis for the alternative plug-in model, the S580e, which uses it in 367hp form, mates it with a 150hp electric motor and offers an impressive 63 mile all-electric driving range.

Top Mercedes-Maybach variants get either a 503hp 4.0-litre V8 or, for the embarrassingly wealthy, a 612hp 6.0-litre V12.

The design of this seventh generation model, though clearly heavily evolved, remains intentionally conservative - the all-electric EQS version of this model makes more of a styling statement.

Boardroom customers though, don't typically want to stand out and will like what's on offer here - a bolder grille flanked by more angular LED headlights that can now feature the brand's latest 'Digital Light' technology.

Every model sold here will get the 'AMG Line' styling pack.

And the slimmer rear lamps replicate a look we've already seen with the large CLS 4-door executive coupe.

This S-Class model's dimensions have grown - by 34mm in length, 55mm in width and 12mm in height.

That's for the long wheelbase model, 110mm lengthier than the 5.18-metre short wheelbase body style that's limited to lower trim levels. Evolution may reign outside, but it's revolution in the cabin, completely re-imagined for a fresh era.

Contrary to expectations, it's completely different to what you'll find in an E-Class or a large Mercedes SUV, the centre dash dominated by a big 12.8-inch portrait-orientated OLED centre touchscreen.

Through the new capacitive double spoke wheel, you view a further digital monitor, a 12.3-inch instrument binnacle display which most variants supply with an innovative 3D display function.

The brand's MBUX media system gets 50% more processing power here - and more intuitive voice and gesture control systems.

And there's a huge head-up display.

The style of the dash is dominated by a large wood panel extending into the doors and is topped by four rectangular vents. Arguably, rear seat space is even more important in a car like this and thanks to this MK7 model's 51mm wheelbase increase, there's now much more of it on offer.

If you choose the lengthened long wheelbase version, as many customers will, there's 24mm more legroom and 11mm more elbow room.At the top of the range, a portable tablet is fitted between the rear seats, which can be removed and used in the vicinity of the car.

Boot space is 30-litres greater than before, rated at 550-litres for the S500 (540-litres for the diesels), though bear in mind that with the PHEV model, that figure falls - to just 325-litres.

If you've reached the point in life where you (or more likely your company) can afford to buy or lease a new S-Class for your use, then price may very well no longer be a determining factor.

Which for Mercedes is perhaps just as well, because it's becoming increasingly difficult to get a well specified version of this model without committing to a near-six-figure outlay.

Still, a premium outlay has never previously put high fliers off from considering an S-Class - or, more likely, another S-Class: around 80% of European customers who've previously owned one return to purchase another Mercedes afterwards.

This lengthier long wheelbase body shape is preferred by over 80% of UK customers - and closer to 90% worldwide.

Which is partly because that's what you have to have if you ignore the two most affordable trim options - which we'll brief you on first: either short wheelbase-only 'AMG Line' (priced from around £83,000) or 'AMG Line Premium' spec (which adds around £7,000 to the price and offers the option of the longer body style for an extra £4,000).

Either way, there are only two engine choices with these two entry-level specs, both of them conventional 3.0-litre six cylinder units; either the rear-driven S350d diesel we tried, with 286hp - still a favourite with British owners.

Or, for around £10,000 more, the considerably gutsier S500 4MATIC petrol-powered version, which has 435hp and AWD to transmit it to the tarmac. If you want a wider choice of engines and an even higher spec, then a range of S-Class long wheelbase model options sit in the £93,000 to £118,000 bracket, with (in order of ritziness) 'AMG Line Premium Executive', 'AMG Line Premium Plus' (which is what we tried) and top 'AMG Line Premium Plus Executive' trim levels available to you.

With these you get two additional engine choices.

One of them is a higher-powered version of the 3.0-litre diesel, the 330hp S400d, which comes with the 4MATIC AWD system and costs around £5,000 more than the base S350d.

The other powerplant is an engine you won't have any choice in selecting if you're planning to acquire this S-Class for private hire registration in London as that kind of activity these days necessitates Plug-in Hybrid tech as a minimum requirement when it comes to engine electrification.

The S580e PHEV petrol model in question (only offered in lwb form) is priced from around £109,000, around £15,000 more than the base diesel.

Saving the planet doesn't come cheap.

Mercedes is keen to talk about its gains in electrified technology here - we'll get to that - but some of these have been offset to some extent by another gain for this seventh generation model - in kerb weight.

It sits on a heavily re-worked version of the brand's 'MRA' 'Modular Rear Architecture' platform and the body now incorporates a much larger proportion of aluminium (60%).

Because of the bigger dimensions of this MK7 design though, this car now tips the scales 55kgs heavier than before, most models weighing in at around the 2-tonne mark. So that explains why we're not seeing class-leading efficiency here; not in the conventionally-engined models anyway.

Let's get to the WLTP figures.

The S350d variant that most customers will choose manages up to 42.8mpg on the combined cycle and 173g/km of CO2.

The alternative S400d 4MATIC delivers up to 38.7mpg on the combined cycle and 192g/km of CO2.

If you go for the petrol-powered S500 4MATIC, you'll be expecting those figures to take a bit of a dip, but Mercedes has compensated here with its 'EQ Boost' mild hybrid technology which features an integrated starter generator powered by a 48V on-board electrical system which enables certain hybrid functions, ultimately improving overall efficiency.

As a result, the S500 4MATIC delivers up to 32.1mpg in standard shape form and emits 187g/km of CO2. To do better, you'll need to ask your dealer about the plug-in hybrid version.

The S580e claims to be the most advanced plug-in hybrid on the market, offering a 28.6kWh battery that allows for a zero emissions range of 63 miles.

It automatically switches power sources when entering an urban area and is compatible with all AC and DC Chargers from 11 to 60kW.

Charging from empty should take only around 20 minutes with a rapid charger.

And the S580e's combined WLTP fuel consumption figure is 353.1mpg and it emits 19g/km of CO2.

The lithium-ion battery can be charged using a DC rapid charger in 20 minutes (10-80%) and two and a quarter hours using an 11kW home wallbox.

This S-Class spearheads technological development, not only for Mercedes-Benz but for the automotive industry as a whole - and has done for decades.

It's that important and is why this is - and will continue to be - the world's best selling full-sized Luxury-sector saloon. In this seventh generation form, this car remains very competitive with - and in some cases a step ahead of - its key Luxury segment rivals.

That was vital if it was going to be able to continue to compete with everything from a comparably costly Audi A8 to a Bentley Flying Spur potentially priced at twice as much.

No other rival has as difficult or as wide-ranging a brief - but then no other car brings this one's timeless clarity and effortless superiority to such an advanced and wide-ranging portfolio of talents. It can power to supercar speeds in Mercedes-AMG guise, deliver an average of over 40mpg in its volume mainstream S350d diesel form and can be specified to eerily steer, power and brake itself at a cruise in whatever form you decide upon.

Yes, other rivals may look more avant garde or handle with a touch more involvement.

In overall terms though, Mercedes has done enough here to enable this S-Class to remain a benchmark for the kind of luxury saloon every prestige brand would like to build.

As it always was, it's a reference point for the current state of automotive technology.

The best car in the world? You'll feel like it is if you buy one.