What's new?
There is not much to report visually. Changes over the CLS55 extend to new badges along the flanks and boot lid, reworked bumpers, new wheels and interior tweaks, including terrific new instrument graphics. Two years after launch, it still looks great – with an added touch of aggressiveness brought by a 10mm suspension drop.

The single biggest change – the one that completely transforms the CLS63’s character from that of the outgoing CLS55 – is its V8. The naturally aspirated unit has been developed from scratch. With 506bhp, it produces a scant 13bhp more than the supercharged 5.4-litre V8 it replaces.

More significantly, the power peak is now developed 700rpm higher up the range than before, at 6800rpm. And with 465lb ft, the CLS63 gives away a considerable 51lb ft to the CLS55.What’s more, it isn’t reached until 5200rpm, some 2550rpm further up the dial.


What's it like?
The word ‘peaky’ comes to mind with those changes. But in reality the new engine is hugely flexible. It lacks the sudden explosiveness of the CLS55, especially at the lower end. The reward, however, is a far more linear delivery. It’s noticeably smoother and throttle response has improved markedly.

I was always a big fan of the CLS55’s thumping nature, but there’s something about the CLS63’s ability to rev higher that ultimately makes it more satisfying.

In straight line terms there’s not much between them, the CLS63 pipping the CLS55 from 0-62mph with a claimed 4.5sec versus 4.7sec: the 500bhp 5.0-litre V10 powered BMW M5 now has a much more focused rival to face up to.

One upside of the CLS63’s lower torque rating (and surely the reason why it’s able to outrun its predecessor) is that it receives Mercedes-Benz’s excellent 7G-Tronic seven-speed automatic rather than the CLS55’s older five-speed ‘box. No conventional torque converter-equipped automatic operates with such apparent efficiency on a wide open throttle.

Try it and you can see why AMG insists its loyal customers don’t ask for anything else. It offers three modes – comfort, sport and manual, the latter of which sees it hold on to each gear, refusing to change up even at maximum revs.

The modifications to the chassis are rather less dramatic than those concentrated under the bonnet. The steering, for a start, is spot on. There’s none of the lightness and vague off-centre feel that affects other Mercedes. Instead, you get a meaty action and a lovely linear action in the first quarter turn of lock.

On the optional 19-inch wheels and 255/35 (front) and 285/30 rubber worn by our car there is massive purchase, the kind that allows you to take big liberties. A spot of tail-out action is there for the taking with the ESP disengaged. The CLS63’s rear-wheel drive chassis more than meets the demands placed on it by its mighty new engine.

Despite the low profile rubber, the ride quality is purposely firm but never crashy. Granted, we’ve only driven it on smooth German roads, but the ability of the CLS63’s air suspension to soak up ruts and ridges is something that marks it out as one of the world’s most accomplished performance saloons – expect that Mercedes would rather that we refer to it as a coupe, of course.

The troubled electro-hydraulic Sensotronic stoppers used by the CLS55 have been replaced by new hydraulic units with 360mm (front) and 340mm (rear) discs. The pedal has a more progressive action and more feel through its travel – all of which provides the CLS63 with huge levels of retardation.


Should I buy one?
Initial impressions are that the CLS63 perhaps falls short of delivering the same sort of crushing performance dished out by its predecessor. But stick with it and you discover it is in fact a much more rounded car: one that’s better to drive, faster where it matters most, more forgiving at the limit and brilliantly supple. It replaces it with a level of finesse you just didn’t get before. In the end, it’s this particular quality that really sets it apart.

E63 for me thanks

It seem like there are quite a few people who don't think the 63 models are more superior than the 55 model. I'm a sucker for torque and the 5.5 engine would probably suit me better than the 63 model.

MB did a mistake, made the Supercharger engine too good. Not easy to top that unless MB start to build a turbocharged AMG's again.

We just got our first CLS63. Yes, I love the 55 but there is something about this built from scratch engine that seems more in tune.

If anyone in the US wants one immediately, ours is for sale.

Yeah, me too. Somehow the concept of a high-revving V8 doesn't click with the effortless autobahn stormer AMGs are supposed to be.