Yahoo Autos 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.
Take a ride on a 4000-rpm launch-control start, and after acclimating to the ferocity of the acceleration, you'll notice what feels like a lazy shift or the engine briefly hitting the limiter at the top of third gear at 76 mph. That's the one-two shift for the rear motor. Even with that little hiccup in the power delivery, straight-line speed is serious—the Mercedes dispatches 60 mph in 2.9 seconds and the quarter-mile in 11.2 at 121 mph. That's 0.7 and 0.6 second quicker, respectively, than the previous C63, although a good chunk of the gain is because this is the first top-dog-AMG C-class with all-wheel drive. For comparison, the last all-wheel-drive E63 S we tested shot to 60 mph in 3.0 seconds.
Although the BMW M3 CS is down a whopping 128 horsepower to the C63, it wins the quarter-mile race decisively. How can this be? Well, given that the Mercedes, at 4749 pounds, is heavier by a monstrous 859 pounds—that's 762 more than the last C63—its power-to-weight ratio barely betters the Bimmer's. But the C63 wins in responsiveness. Check out the 3.6- second time to 60 mph from a 5-mph rolling start, 0.4 second ahead of the BMW. It beats the Cadillac CT5-V Blackwing too. See also the 2.3-second 30-to-50-mph time, which bests the M3 CS, even though the C63 starts this test with its engine off in Comfort mode (we perform passing tests in a car's default drive mode). In Race mode, the 30-to-50-mph passing time drops to 1.5 seconds, which is electric-car territory.
The e-turbo itself finally delivers on its promise of lag-free boost and is far more responsive than the similar setup in the C43. Part of the improvement is certainly that the C63's e-turbo operates on 400 volts, while the lesser AMG's is a 48-volt unit.
We pull off at a scenic overlook to take in the views, where the light-colored rocky outcroppings meet the deep-blue Mediterranean Sea. Much of the vegetation below comprises the grapevines prevalent in this Provence region.
Unlike the powertrain, the C63's exterior is quite subdued. There's a modest front splitter, rear spoiler, and central hood vent. Additional vents on the front fenders incorporate E Performance badging. Perhaps AMG spent all of its budget and then some on the powertrain, but there's no carbon-fiber roof or anything extraordinary on the outside. There aren't even carbon-ceramic brake rotors.
On the other hand, the C63's modes and displays are consistent with the level of powertrain complexity. There are displays that show the temperature of each motor and the real-time power and torque of each source. One of the gauge-cluster display options has the engine rpm radiating outward like a blast zone, while spears of light jut out to indicate electric-motor output. Bar graphs on the periphery show the power and torque output of each of the two major propulsion sources. Two knobs on the steering wheel control the many adjustments for the overall mode, as well as individual tweaks for the dampers, amount of regenerative braking, stability-control settings, engine-sound enhancement, and more. AMG has even mapped out the optimum electric deployment for numerous racetracks, showing the driver where to push past the throttle detent for maximum motor boost and where to back off and let the battery recharge.
Back at a sedate pace, there's also some nominal electric-only capability at speeds up to 78 mph: eight miles on the European cycle, which should equate to roughly seven in the U.S. We saw between four and 10 miles, depending on conditions. Part of the reason is that the engine comes on with 25 percent of the battery remaining to ensure there's always a buffer to provide an acceleration boost on demand. But the small 4.8-kWh battery recharges quickly—roughly an hour on a 240-volt outlet or about 10 minutes if you select Race mode, where the gas engine aggressively recharges the battery.
Why go to all the trouble to tame this complexity? Well, U.S. fuel-economy figures aren't available yet, but the C63 is about 50 percent more efficient than the M3 CS in European fuel-economy metrics. That's massive but, of course, based on dipping into very little of the Mercedes's power reserves. The 17 mpg we averaged is perhaps impressive compared only to what we might have burned with its V-8-powered predecessor. And in Europe, where a tank of premium can easily run more than a decent hotel room, fuel economy certainly matters more. The price is also up substantially, to a starting point expected to be right around $100,000.
We're impressed by the C63's integration and that it doesn't feel as complex as it is. But AMG's latest triggers more of a left-brain crush than unqualified passion. We miss the V-8.
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