Consider the evidence. This is a car that is fitted with a 518bhp V8, rear-wheel drive, and thoroughly clever not-quite-a-DSG-but-close 7-speed transmission (of which more later). It can also hit 62mph from rest in 4.5 seconds.
And yet it is a car that seems desperate to play the role of normal executive saloon. Put the gearbox into 'C', for instance, (which admittedly denotes 'controlled efficiency' rather than 'comfort') and the gearbox will shift up as soon as is sensibly possible to keep the engine speed as low as possible, moving you off in second gear and engaging sixth as low as 37mph.
Having said that, the four-mode gearbox does seem to be equally at home playing the full-on flappy-paddle mentalist (it even allows you to bounce off the rev limiter in manual mode without changing up) as it does doing the relaxed cruiser thing.
But despite all the muscle-saloon ephemera the overall effect is somehow less aggressive than you'd expect. Unless you park a more humble E-class next to an E63 your average passer-by, if they notice it at all, will simply see a mildly tweaked Stuttgart taxi. AMG enthusiasts will notice, however, and perhaps that's all that matters.
And the AMG tweaks that are there - comfortable but supportive electrically adjustable sports seats and a four-spoke AMG sports wheel with shift paddles - add an understated air of sportiness without compromising everyday comfort.
As the road opens up and the traffic thins out, your attention will turn to the rotary knob to the right of the stubby shift selector, and the three buttons below that. These form the AMG Drive Unit, and allow you to choose between four different gearbox modes, two different suspension settings and three ESP modes. All of which is, frankly, a bit of overkill, but it really does make quite a difference.
Now the old girl really hurls herself down the road with enthusiasm. The stiffer ride controls lateral and vertical body movements without wrecking the ride quality, the gearbox suddenly allows the big V8 to bellow its power out across the rev range rather than changing up at the first opportunity, and the ESP permits you the small amount of slip that makes you feel good about your driving but with the full knowledge that it will catch you should you become over-exuberant with your right foot.
Mercedes was kind enough to book out the Top Gear test track at Dunsfold in Surrey for us to play with and, although the temptation to have a go at a Stig-style power lap was pretty major, it was easily overwhelmed by the lure of smoky slides. Well, okay, not smoky as there was a fair amount of water on the track, but the point is that, given enough space, the E63 becomes a lovely thing to fling about beyond its limits of grip. It's well balanced, the big bhp and wide, linear power band allow an amazing amount of adjustment on the throttle, while the faithful steering and long wheelbase make silly behaviour an eminently controllable activity.