Tested: 2024 Mercedes-AMG C63 Is the Quickest C-Class Ever

From the March/April 2024 issue of Car and Driver.

There's a concept popularized by the English philosopher William of Ockham in the 1300s. Called Occam's razor, it advises that, when given multiple hypotheses with equal explanatory power over a phenomenon, the simplest answer is most often the right one.

For example, say a compact German performance sedan accelerates to 60 mph in under three seconds. You'd suppose it's sending power to all four wheels, and it's possibly electric. But you wouldn't float a theory that it's a plug-in hybrid where, even in Electric mode, it can shift between rear- or all-wheel drive or that its electrified turbocharger can recharge the battery. But, in the case of the Mercedes-AMG C63 S E Performance, this more complicated explanation is correct. Occam's razor evidently doesn't cut it with engineers in Affalterbach.

Perhaps AMG was looking for a fresh challenge after installing a very nearly Formula 1 powertrain in its One hypercar. But this is arguably the most complex powertrain in the new-car market, which is saying something in this era of blended combustion-and-electric propulsion. In total, this highest-performing C-class makes 671 horsepower and has three electric motors. The most powerful one gets its own two-speed gearbox and spins coaxially with the rear axle. Another motor hangs off the front of the most powerful production four-cylinder engine ever. And AMG integrated the third into the turbocharger, primarily for preemptive boosting to minimize lag. Comprehending all of it requires a diagram [see "AMG's New Plug-In-Hybrid Math Explained"].

With the C63 not yet available in the United States, we decamped to the South of France for a thorough wringing out. (Why not simply call it southern France, you ask? The French labels just aren't that simple.) Trundling through low-speed stop-and-go traffic, we find it remarkable how seamlessly and harmoniously the C63's powertrain works together. We often joke that a bad vehicle can feel like a collection of parts flying together in close formation, but the C63 instead could feel like a collection of power trains. In the default Comfort mode, the engine turns on and off regularly and does so very smoothly, more so than some shifts, despite its high-strung nature—469 horsepower, 235.6 horsepower per liter, and 23.0 psi of peak boost. But this latest and most powerful incarnation of the M139 2.0-liter inline-four can sound reedy and buzzy under these conditions; in other words, it can sound like the generator it sometimes is.

Making our way to the coast southeast of Marseille, we encounter narrow roads barely a lane wide in small towns, and the modestly sized C-class instantly feels more like an S-class. France has odd trapezoidal speed bumps that are roughly the same size as a vehicle's track width and meant to be straddled. Once clear of those, we become aware that the signs depicting a sliding car and reading Verglas Fréquent (literally, "frequent ice") mean we're getting close to the best roads, the ones that appear to have been paved by a dog chasing its tail.

There's road texture coming through the steering wheel, and the on-center effort is a deep vee, sneeze-proof at unlimited autobahn speeds. There's also appropriate damping on-center, which we much prefer to the BMW M3's latest tuning. Turn-in is eager, but the effort ramp-up from there is a bit flat and subtle. In Sport mode and above, the engine stays on continuously and adds pops and crackles in heavy-throttle driving. Optional AMG Performance front seats are very supportive, especially in the thigh area, and not nearly as constrictive as BMW's, with adjustable side bolstering and lumbar. The back seat is adult-habitable but not generous.

At max attack, the engine sounds urgent but not invigorating. Interior noise is a polite 78 decibels at wide-open throttle, a far cry from the 83 decibels of this C63's fire-breathing V-8- powered predecessor. There's more rearward power balance and willingness to corner neutrally in Sport+ and Race modes. But things don't get hoony until you select Drift mode, which puts all the power to the rear axle and requires manual-shift mode and the commitment of switching the stability control all the way off. And even then, the C63 doesn't bite. Dynamically, it's very confidence-inspiring.

The ride quality is firm, but it's more roll stiffness than ride harshness. Undulating roads can induce head toss, which is no surprise considering that the massive anti-roll bars could pass for plumbing stock. The brake pedal is squishy at the top of its travel—a knock on the tuning rather than the very capable brake hardware that produces stops from 70 mph in a ridiculously short 139 feet, partially due to a test surface that's likely grippier than our norm.