Smoothly, quietly and confidently, a silver Mercedes-Benz S-class casually wafts along an autobahn outside Stuttgart.

The S500’s twin-turbocharged 4.7-litre V8 is barely audible as the automatic gearbox picks up seventh gear with a velvety shift, dropping the revs back under 2000rpm for truly tranquil fast-lane progress. Save for some distant tyre rumble and a faint lick of wind across the roof, there is a remarkable calmness at an indicated 100mph. The car gathers miles effortlessly, pampering its occupants with low levels of noise and miraculous ride comfort.

This sixth-generation S-class promises big things. Its predecessor was an enduring favourite, so expectations surrounding Mercedes’ flagship have been mounting ever since it was revealed in May. The advanced four-door is a rolling fortress of technology, all of which aims to place it at the top of the luxury car ranks ahead of the Audi A8, BMW 7-series, Jaguar XJ and Lexus LS.

Mercedes-Benz chairman Dieter Zetsche acknowledges that this S-class has a vastly different mission from the one it replaces. It will be produced in no fewer than six different variants, including initial short and long-wheelbase models, followed by an extra-long-wheelbase model within the next year. This new variant, we’re told, will offer a limousine-like experience to match the Bentley Mulsanne and Rolls-Royce Ghost and is planned to be the basis for a return of the Pullman. There will also be a two-door coupé and a cabriolet.

Mercedes’ efforts at updating the S-class’s appearance have been a success. The exterior styling, with greater sculpture to the body, evolves the appearance without straying too far from the outgoing model. A more prominent grille and larger, more angular headlights provide quite a noble appearance, while a prominent swage line adds greater intrigue to the flanks. There is little change in external dimensions over the old S-class in the long-wheelbase model tested here, the new car being just 21mm longer, 29mm wider and 11mm higher than before.

The S-class’s aerodynamic properties are class-leading. Official figures point to a drag coefficient of just 0.24, with further refinements set to net the S300 BlueTec Hybrid an even more efficient 0.23 thanks to adjustable louvres in the cooling system, extensive underbody panelling and detailed work to the wheel houses.

The S-class’s body has been thoroughly re-engineered and its entire outer skin is now made from aluminium. The internal structure uses aluminium in combination with hot-formed high-strength steel and a number of plastic components but, despite this, the S500 driven here has actually gained 5kg, hitting the scales at a claimed 1940kg. Offsetting the slight increase in weight is a dramatic increase in rigidity, which provides the basis for a reduction in vibration and an even smoother ride.

The engine line-up remains much the same as for the outgoing model. Included from the outset will be a 3.0-litre V6 diesel with 254bhp in the S350 BlueTec and a 2.1-litre, four-cylinder diesel with 204bhp in combination with a 27bhp electric motor for a total output of 228bhp in the S300 BlueTec Hybrid. They’re both exceptionally efficient, with combined cycle figures of 56.5mpg and 64.2mpg respectively. Between them, they’re expected to account for almost 80 per cent of UK volume.

Also planned for the UK is the S400 Hybrid. It uses a carry-over petrol-electric powertrain that consists of a 302bhp, naturally aspirated 3.5-litre V6 and 27bhp electric motor for a combined economy figure of 44.8mpg. Our drive, however, is of the initial range-topping S500, the best-selling S-class model globally and one of the new models set to arrive in the UK this autumn.

It runs a twin-turbocharged V8 that produces 449bhp at 5250rpm, 20bhp more than in the old S500. Torque remains at 516lb ft at 1800rpm, and drive continues to be sent to the rear wheels through Mercedes’ 7G-Tronic seven-speed automatic gearbox. A four-wheel-drive 4Matic option will be offered in selected markets, but it is not destined for the UK.

The new S-class’s design reflects the influence of a new generation of Mercedes-Benz designers. Inside, there is an elegant simplicity to the dashboard, which neatly wraps around into the doors. Creature comforts include optional heated armrests, a hot-stone massage function for the front seats, an active perfuming system and a brilliantly effective 24-speaker Burmester High End 3D surround sound system.