The fifth Mercedes-Benz to wear Black Series badging may be neither the most powerful, nor have the highest top speed (both accolades belonging to the 670bhp, 199mph SL65 Black Series).

In terms of real world, point to point performance, though, it is by a gigantic margin the quickest Mercedes Benz production car to head out onto the public road. And that's including the SLR McLaren in its myriad guises.

While it is tempting to focus on what you can see – all those slats, spoilers, fins, chins, wings and winglets – and what you can hear – the additional 59bhp bequeathed upon its venerable 6.2-litre V8 to bring its total to 622bhp, far more light is shed upon the real character of the car by what the eye and ear are unable to detect.

You’ll not be far along a slippery British B-road before you become startlingly aware of just how different is this car to a standard SLS.

You notice the ride first which, thanks to springs rates that have risen overall by almost half as much again, is uncompromisingly harsh to say the least. It’s not bone-jarringly uncomfortable, because the dampers have the sophistication to take the sharpest edges off the worst bumps, but it feels like it’s been set up to do its best work on track, in much the same way as, say, an old 911 GT3 RS.

As you raise the pace, it becomes clear there’s more than mere power making this car respond like you’re prodding a rattlesnake with a stick. There’s less weight too, 70kgs of it to be precise, dropping the already slimline SLS’s kerb weight down to just 1550kg which is less than a base spec C 200 CDI saloon and, perhaps more relevantly, 80kg less than a Ferrari F12.

But it’s the combination of a rev range extended all the way to 8000rpm and gearing dropped through the floor that keeps this car coming on and on at you. I lost count of the number of times I pulled a paddle to call for an eighth gear that’s not in the box.

Driving fast on a cold, dark and damp pre-dawn morning in the Welsh Marches forces the new electronic diff and every stability system into an intense overtime. Because of the immense width of its body and hair-trigger response of its throttle, this is not an easy car to drive slowly.