The engine builders at Mercedes-AMG will soon be making only three power units: the 2.0-litre turbo four-pot from the A 45, the 4.0-litre turbo V8 from the new GT and the 6.0-litre V12 from the S 65.

The 5.5-litre V8 in this car is living on borrowed time, yet it suits the S 63 so well that you could imagine it finding a home in the car for years to come.

Matt Saunders Autocar

Matt Saunders

Road test editor
The all-aluminium V8 produces 577bhp and 664lb ft

The V8’s creamy balance blends with enough aural character to let you know you’re driving a performance car, but with a lot more torque and mass-defying oomph than its noise level ever conveys.

On a damp day, it propelled this 2.1-tonne luxury grand tourer to 100mph in less than 10 seconds. That’s more than a second quicker than the last W12-engined Bentley Continental we figured and nearly two seconds quicker than the Aston Martin Rapide S. So there’s no need to question the wisdom of accepting eight cylinders when you could have 12 for the same money elsewhere.

Perfectly consistent mid-range performance is the S 63’s strongest virtue. Pulling from 40-60mph in fourth at matter-of-fact crank speeds takes just 3.0sec; in the same gear, getting from 90-110mph takes just a couple of tenths longer. Aston Martin’s just-replaced six-speed Rapide S is no less than 30 percent less flexible – and the new eight-speed version can’t be much closer.

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The wonder of such mid-range muscularity is that it filters into every brush of the throttle pedal. The S 63 never feels its mass, while the torque delivery is such that the transmission’s shift strategy can be blissfully laissez-faire. The performance is there the instant you want it – partnered by outstanding wind and road noise suppression.

Savage acceleration wouldn’t do for a devoted grand tourer, but the fact remains that GTs don’t come much quicker. Furthermore, a standard-bearing car on outright performance has no right being so refined.

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