Downsizing and electrification clearly agree with the C63's spec sheet, but what about its demeanor? A drive across southern Spain, which is where Mercedes hosted the C 63's media launch event, and a couple of hot-lap sessions at a racetrack reveal this is a C 63 like none before. If there has been a more radical transformation of a single model's powertrain and character between generations, we haven't experienced it. Whereas previous C 63s were renowned for their V8 bellow and gloriously unhinged rear-drive nature, this generation is marked out by its sophistication and polish.
On track, the C 63 occasionally feels like it could use more grip than its Michelin Pilot Sport 4 S rubber can muster. But on the region's winding coastal roads, the tires' blend of stick and ride compliance is well chosen. With so much power, you might reasonably expect this sedan to be a twitchy, high-strung beast. It's not. That's partly because AWD gets all that power down smoothly and without drama, and partly because the addition of four-wheel steering results in adroit cornering.
But a key component in the C 63's newfound civility is AMG's decision to carefully silo the powertrain's boost reserves depending on drive mode. The computer won't unlock full boost outside of the car's Race mode, and you still have to carpet the pedal and push past the accelerator's kickdown detent. Even Sport+ only activates 80% boost. This car doesn't feel like it has nearly 700 horsepower because, most of the time, it doesn't.
Unfortunately, all of this means that outside of Drift mode — the hilariously rewarding tail-happy-but-controllable nature intrinsic to C 63s of yore — is utterly absent, smothered under the heavy weight of batteries and sophisticated electronics. Mercedes says the C 63 weighs 4,828 pounds, which is already over 900 pounds more than an AMG C 43.
This is further compounded by the lack of a stirring soundtrack. Yes, Sport+ and Race trigger more aggressive noises (electronically augmented sounds are piped through a series of speakers both inside and outside the car), but it's not the same. AMG engineers may blame the increasingly draconian pass-by noise regulations in various world markets, but we suspect that existing C 63 owners will nonetheless be disappointed by how straight-laced this new model sounds.
Another thing that takes a little getting used to when driving hard? Slowing down. There are various user-selectable levels of regenerative braking, from Level 0, which feels like braking in a traditional gas car, to Level 3, which is similar to the one-pedal mode found on most EVs. That's all well and good, and pedal feel is pretty good. But it can take a bit more pressure than one might expect to slow from very high speeds on track, likely an artifact of the C 63 weighing just 240 pounds less than the last Mercedes S-Class (S 580 4Matic) that we tested.