First Drive: Mercedes‑AMG GT 63S Four Door

But get past the name to the car beneath and you’ll find Mercedes’s new Porsche Panamera rival to be one of the most surefooted new cars of recent times, and I mean that both literally and figuratively.

Whatever you call it, the new car is the second standalone AMG on sale, after the GT coupe which itself was begat by the gullwing SLS. Unlike its older, swoopier sister the Four Door does not sit a bespoke architecture, but a heavily adapted version of the platform that underpins – among many other cars – the E-class saloon. But it shares no significant dimensions with any other Benz nor any body panels so can rightly be considered an entirely new car.

Under the bonnet comes the most powerful version of the company’s increasingly ubiquitous 4-litre V8, pumping out some 631bhp. Moers intimated that this was probably about as far as the engine would be allowed to go, with future powertrains made more powerful not by additional boost pressure, but the addition of hybrid drives.

Inside the car is precisely as you’d expect: a world where soft leather upholstery lives in relative harmony with a space age and almost infinitely configurable dashboard of ultra-high def TFT screens. If you’re a certain sort of person you could while away plenty of happy hours just figuring out how it all works. Or you could instead thumb a button, power up a V8 that puts more powerful under your right boot than did the McLaren F1, and head out onto the track to find out more.

The track? It doesn’t look like a track car and if you sit in its spacious rear cabin with room to spare for two six foot adults or even three if you specify a bench rear seat, it doesn’t feel like one either. But climb into the seat with the wheel and soon this super civilised land-bound executive jet is doing things you’d been pleased to see from a purpose built sports cars, let alone something sitting comfortably the wrong side of the two tonne mark.

The secret, I am told, lies in the way its many and varied chassis systems interact. It of course has a very sophisticated four-wheel-drive system but four-wheel steering too. It has electronically controlled differentials and electronically controlled springs and dampers too plus, naturally, a range of driver selectable modes for the electronic stability systems depending on you’re happy for the car to feel. All of which should make the car feel like an arcade game. But it doesn’t. On the contrary and where it is supremely clever, all this technology contrives to make the car feel pleasingly analogue, responsive and communicative. It grips hard but also slides at will if that’s what you want. For a car of its size and mass, it is profoundly impressive.

Nor is it any less so when you leave the artificial environment of the race track and head out onto the road where, of course, almost all Four Doors will spend almost all their time. The car is quiet and comfortable enough at least in Texas to convince in the role of long distance tourer, though the needlessly hard optional sports seats are to be avoided. It will be interesting to see if the car retains sufficient suspension compliance to cope with the somewhat sterner challenge posed by our more broken road network. But here or there, few will quibble with the quality of the interior fitments, the car’s innate sense of strength or the clarity with which it conveys somany terabytes of information.

Sales begin next month with prices for the 63S model starting from a fairly eye-watering £135,000. There is a ‘standard’ 63 with a trifling 585PS (577bhp) rather than the 640PS (631bhp) of the S, but few are expected to save around £15,000 and have to explain why they didn’t go for the full fat option.

In the US and elsewhere a GT 53 version is also available with a 435PS (429bhp) 3-litre straight-six aided by a 22PS mild hybrid, and while that powertrain does sterling service in less sporting Benz products like the E-class saloon and CLS coupe, in the Four Door it serves mainly to remove a chunk of the car’s charm. It’s not the outright power you miss so much as the thunderous soundtrack and the immediacy of the V8’s torque-laden response. Mercedes-Benz is still evaluating whether to bring the 53 to the UK; were I them, I’d probably not bother.

But the 63S is an unlikely gem. Far from being a poor relation to the AMG GT Coupe, the Four Door brings a massively broader range of abilities yet loses only a little of its sister’s depth. Of course the two door coupe is quicker, though even the titan GT R is less powerful, but the Four Door is the easier car to drive, with a far more friendly nature. Drivers of less than unusual skill may therefore also consider it more fun.

This, then, is AMG’s most assured product to date and a welcome addition to a class of car that, with the likes of the new Panamera, BMW 8-series and Audi RS7, is getting not only bigger but, on this evidence, considerably better too.