While the BMW M4 is technically brilliant and super-quick around a race track, it can feel a little sterile when you’re just trying to pop to Tesco. Not so with the C63. Perhaps it’s slower against the clock if you plan to spend more time lapping Monaco than on the M25, but, like the Giulia QV, it’s big on theatrics, and this arguably makes it more fun for everyday use.
Start the big V8 petrol engine and it thunders away like an old American muscle car, and even more vehemently when you switch on the sports exhaust (standard on the coupe and convertible but optional on the saloon and estate). It sounds heroic simply dawdling along in traffic – or when navigating a multi-storey car park – and the noise is especially enjoyable in the convertible with the roof down.
Mash the accelerator, though, and you’ll discover that there’s more to the C63 than just noise; it’s a full-on performance machine. The coupe is the quickest version, trailed fractionally by the heavier saloon, estate and convertible, but you'd struggle to tell the difference in pace without using a stopwatch.
There’s also minimal delay between planting your foot and the turbochargers winding up, which makes the C63 perfectly predictable despite all that poke. Then, once its potential is realised, the C63 builds speed like a dropped dumbbell.
The S version, with its extra 34bhp, is quicker still and adds that final layer of excitement, and is our favourite for this reason. It also unlocks an optional AMG Driver’s Package, which ups the top speed to 180mph from the standard, electronically limited 155mph. However, you won’t feel underwhelmed by the standard model, which only takes a tenth of a second longer to roar from 0-62mph, requiring 4.1 seconds rather than 4.0. And, despite the pent-up rage beneath the bonnet, the C63 is generally as docile and easy to drive as any regular C-Class when your head’s in ‘drive sensibly’ mode.
The nine-speed automatic gearbox is pretty good but not the best. It’s a tad jerky when you're trying to park and its shifts aren’t as punchy or responsive as those of the Giulia QV. It's smooth enough once you're up and running, though.
The only frustration you might face when letting the C63 off the leash, comes when using the gearbox in manual mode. The system imposes a delay before you can change up if you let the engine reach its soft rev limiter, which cuts in after peak power is delivered between 5500 and 6250rpm. You’ll need to learn to shift at the right point for the smoothest, fastest drive.
Meanwhile, you can alter the feel of the C63’s suspension with a mode switch on the centre console. In the softest Comfort mode, the ride is firmer than the Giulia QV's in its equivalent setting, but the C63 still has just enough give that it never crashes too harshly over bumps, even if it does thud over sharp ridges and deep potholes. It traverses larger obstructions, such as speed humps, surprisingly well, too.
For quick driving, Comfort mode keeps body roll well checked, but the best setting for making the most of country roads is the midway Sport or even the firmer Sport+. Both modes make full use of the C63's nimbleness, allowing it to change direction extremely quickly for what is a comparatively heavy car. It matches the delicate balance and adjustability of the Giulia QV and completely trounces the stodgy and wayward RS4 Avant for driving pleasure.
There's a mass of grip, too; in fact, considering the power at play, the C63 is surprisingly docile. If you find yourself on a race track, meanwhile, Race mode further relaxes the C63’s electronics to allow a little wheel-slip before the traction control cuts in, and experienced drivers can choose to dial the settings back still further. That's a big boon over the Giulia QV, in which the traction control is a binary on or off.
The standard C63 has a mechanical limited-slip differential, while the electronic differential in the C63 S makes it even easier to control on the limit. And when its driven rear wheels do lose purchase, the resulting slide is easier to manage, and therefore arguably more fun, than in the snappier M4.
Meanwhile, the steering is a pleasure. It’s not overbearingly heavy around town and weights up beautifully as you build speed through turns, with plenty of feedback through the steering wheel. That means you can feel confident when placing the car on the road and encourages you to push a little harder.
Whichever bodystyle you choose, the C63 will eat up the miles when you need it to. Wind noise is pretty hushed at speed, and, while you have to put up with a bit of road roar from the fat rear tyres, it’s not overbearing. Mind you, it's fair to say that overall refinement is one area in which the RS4 Avant has the C63 beaten.