Tested: How the Mercedes-AMG C63 S E Performance Lost Its Way

For six years, the Mercedes-AMG C63held an exclusive lock on V-8 engines among compact German sport sedans. Compared to six-cylinder peers from Audi and BMW, it hardly mattered which car claimed the best design or the most luxurious interior or the sharpest handling when you uncorked AMG’s 503-hp V-8. The twin-turbo 4.0-liter (and the beastly naturally aspirated 6.2-liter V-8 before it) had a way of sucking the air out of any debate and shouting down the competition with its glorious bellow.

But the small sport sedan with the big engine is no more. The 2025 Mercedes-AMG C63 S E Performance replaces the thundering V-8 with a brainy plug-in hybrid system that combines one four-cylinder engine, two transmissions, and three motors to shock all four tires with a spectacular 671 horsepower and 752 lb-ft of torque. 

From an engineering perspective, AMG’s latest lab-made monster is a technological marvel. This is easily one of the most complicated automotive powertrain to ever reach mass production, which might be why the car it powers is so difficult to comprehend. Saddled with a roughly 800-pound weight gain and lacking the V-8’s hallmark roar, the C63 S E Performance muddles its incredible power in a blur of contradictions: ferocious yet quieter. Refined but violent. Objectively awesome and subjectively disappointing. Simultaneously better and worse.

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Making the Complex Appear Simple

Rip around town or hammer down a squiggly backroad, and the C63 hides its complexity behind a fluid stream of thrust. So smooth is the power delivery that, if you didn’t know otherwise, you’d never suspect that every flex of your right ankle started a ballet of air molecules, atomized fuel, exhaust gases, and electrons. Pin the accelerator, and the rear-mounted motor jolts the tires with up to 203horses and 236 lb-ft. The second motor spins the turbo up to speed in the same instant, pressurizing the engine’s intake manifold faster than you can say “no lag.” This electric immediacy provides cover as the nine-speed transmission kicks down to close the distance to the engine’s 469-hp peak at 6,750 rpm, where the pistons pump out enough exhaust to spin the turbo without electric assistance. As you reach extralegal speeds, the second transmission—a two-speed gearbox mounted at the rear axle—shifts into high gear, giving the traction motor a second wind right when most motors start giving up. The third motor, sandwiched between the 2.0-liter engine and its nine-speed automatic, starts the engine and turns the crankshaft’s motion into electricity, but it doesn’t contribute torque to drive the car.

All this happens without so much as a dip or a blip in the buttery power delivery. The electric and combustion components work so well together that you might think AMG has been building powertrains like this one for years. Considering the conceptual similarities between the C63’s plug-in hybrid system and a Formula 1 power unit, it kind of has.

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Launched Into an Alternate Reality

Did we say the C63 S E Performance is smooth? It is right up until it isn’t. With the steering-wheel mode selector dialed to Race, launch control is an entirely different experience. The engine spins to 4,000 rpm to help the rear motor fire the C63 off the line with the urgency of an EV. That deception lasts barely more than a second until, somewhere around 30 mph, the engine takes a breath during the first upshift and the nine-speed slams into second gear. Your head bobs forward and then snaps against the seat back as if you drive the car into a bounce house and moments later are rear-ended by a garbage truck. Shifts into third and fourth are only slightly less violent.

These palpable torque interruptions feel slow, but it’s another deception. Your body’s sense of speed gets scrambled by how quick things happen in this car. Our Vbox test gear captures what our meat suits can’t: The plug-in C63 hurtles from 0 to 60 mph in 3.0 seconds, buzzes to 100 mph in 7.2 seconds, and streaks through the quarter mile in 11.3 seconds at 121.0 mph. That’s a full second quicker to 60 mph than the V-8 C63 S AMG Mercedes launched a decade ago with a seven-speed transmission. 

Hold your applause for the gas-electric bits, though, because the real hero behind the C63’s quickness is the all-wheel-drive system. The 503-hp BMW M3 Competition xDrive runs neck and neck with the Merc through 60 mph and beats it to the quarter-mile marker by 0.2 second without any electric helpers. It also weighs nearly 1,000 pounds less.

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Can Someone Turn the Volume Up?

The E Performance powertrain can get your heart racing, but speed alone won’t make you fall in love with it. The four-cylinder struggles to evoke emotion, both at the track and on the road, largely because of the noises it makes—or, more accurately, doesn’t make. In the most generous interpretation, the Mercedes-AMG C63 S E Performance sounds like a slightly louder Volkswagen Golf R. VW’s ubiquitous turbocharged 2.0-liter inline-four powers everything from the Atlas three-row SUV to the GTI hot hatch, all with a deep, flat thrum. The C63’s similarly monotonous growl lacks the texture, depth, and personality of eight cylinders belching hot air. The C63’s plug-in powertrain sounds demure even compared to a Mercedes-AMG CLA45’s rowdy four-banger. That makes us think turning down the volume and intensity was a choice—the wrong choice.

What’s the Point of the Plug?

Another head-scratcher: Why does the C63 even plug in at all? Storing just 4.8kWh of electricity, the lithium-ion battery is small for a plug-in hybrid and EPA-rated for a measly 3 miles of electric range. Mercedes says the system is designed for performance rather than electric driving or efficiency, which we can confirm after plugging it in multiple times per day and managing 19 mpg-e. That matches the energy efficiency of the V-8 car hitting its 19-mpg EPA combined rating.

The battery drains fast when you ride the C63 hard, but by capturing energy from the turbocharger and the starter-generator motor and via regenerative braking, it recharges to full after just a few minutes of spirited driving in Race mode. Since electric motoring was never the point and the car can quickly refill the battery on its own, plugging it in is pointless unless you’re bent on saving a few nickels fueling a car with an $87,200 base price.

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A Major Weight to Contend With

Rear-wheel steering and an electronically controlled limited-slip differential impart an athleticism that defies the E Performance’s 4,818-pound curb weight. While you wouldn’t call it playful, the C63 changes direction eagerly and predictably, and the Michelin Pilot Sport 4S tires hang on with 1.00 g of cornering grip on our figure-eight circuit, where the AMG laid down a 24.0-second lap. That’s good but not great. The all-wheel-drive M3 Competition laps the course in 23.3 seconds and delivers far more fun in the process.

At the limit, the AMG’s steady-state handling balance leans strongly toward understeer. Carrying a neutral angle through the bends requires trail braking deep into the turn to shift the weight bias from the tail to the nose. That’s easier said than done, though, because the brakes and tires are so brutally effective at scrubbing speed—see the 99-foot stop from 60 mph as proof. You’ll have to keep the throttle pinned beyond your comfort zone to get it just right. On rare occasions when the C63’s tail does let go midcorner, the rear snaps around quickly and without warning, requiring fast and precise hands to catch the slide. It’s a much more forgiving beast exiting under power, when it will do a happy little tail wag.

A quick variable-ratio rack lets you steer from full left to right lock in less than two turns of the suede-wrapped flat-bottom steering wheel. That makes for immediate and direct responses, and yet the car never feels darty or nervous on the highway. We do wish the steering weight built up more off-center and that the effort wasn’t so light as the wheel returns to center. 

The ride quality is a mixed bag. AMG’s adaptive dampers work miracles on Michigan roads, but no matter how much harshness they soak up, there’s simply not enough travel in the suspension to be truly comfortable. With nowhere for the wheels to go, the C63’s body pitches and rolls over anything but the smallest bumps.

Just Because You Can…

From a distance, the C63 appears to do everything it did when there was a V-8 engine under the hood and then some. It’s a suede-lined rocket of a car with a mind-boggling powertrain and a wince-inducing price, especially at $103,440 as tested. Making the ambitious plug-in hybrid system work so seamlessly must have taken serious engineering resources and skill, but the bigger challenge for AMG is convincing anyone the E Performance powertrain is a suitable replacement for the loud and proud V-8, which could have been every bit as quick if AMG had just paired it with all-wheel drive. Without the eight-piston percussion assaulting your eardrums, it’s quiet enough in the C63’s cabin to hear your own thoughts, which in my head sounded a lot like Jeff Goldblum playing Jurassic Park’s Ian Malcolm: “Your scientists were so preoccupied with whether or not they could, they didn’t stop to think if they should.”