2025 Mercedes-AMG GLC63 S E Performance Gets It Done the Hard Way

The moniker that’s attached to the new top-dog Mercedes-AMG GLC—2025 Mercedes-AMG GLC63 S E Performance—is the first indication of the newfound complexity of this extreme machine. AMG’s signature product was once known as the Hammer, a simple but effective tool. You wouldn’t call AMG’s new GLC simple, but it’s undeniably effective.

The source of motivation is the biggest change versus the previous generation. That model used a twin-turbocharged 4.0-liter V-8 that somehow managed to channel the brawny character of AMG’s big naturally aspirated 6.2-liter V-8. Now, AMG has chopped the cylinder count and displacement in half, switching to a 2.0-liter turbo four—but before you walk away in disgust, listen to this: 671 horsepower!

To reach that lofty total, the heavily boosted M139l four (itself good for 469 horsepower—an incredible 236 horsepower/liter) is teamed with a rear-mounted electric motor. The motor delivers up to 201 horsepower and is fed by a 4.8-kWh battery that can be charged by either engine or cord, making this a plug-in hybrid. There’s also an electric motor on the shaft linking the compressor and turbine wheels that spools up the turbo; it also keeps the snail spinning when the driver lifts off the gas. There’s a 400-volt system to run that e-motor (and to facilitate the automatic stop-start system). A nine-speed automatic transmission again employs a clutch pack rather than a torque converter, and the rear motor gets its own two-speed gearbox. Finally, the 4Matic+ all-wheel-drive system can distribute the torque from the engine and e-motor to either axle in any percentage from 50/50 to 100 percent rearward. Aside from minor details, this is the powertrain from the 2024 C63.

There’s plenty going on underneath this SUV as well. The latest GLC63 trades the previous air springs for steel coils, paired with retuned adaptive dampers that now provide a greater range of adjustability. There are also active anti-roll bars, which necessitate their own 48-volt electrical system. Rear-wheel steering is another new addition. With a factory-stated curb weight of nearly 5100 pounds, the brakes need to be beefy and they are, with 15.4-inch discs up front and 14.6 inches at the rear.

The GLC63 S E Performance “enables a previously unknown variety of driving experiences,” says Steffen Jastrow, director of vehicle development at AMG. To that end, there are no fewer than eight drive modes (Slippery, Individual, Battery Hold, Electric, Comfort, Sport, Sport+, and Race), chosen via the steering wheel’s starboard dial. They mix and match three levels of adaptive damping (Comfort, Sport, and Sport+), seven powertrain settings (Reduced, Battery Hold, Electric, Moderate, Sport, Dynamic, and Race), and four AMG Dynamics levels (Basic, Advanced, Pro, and Master—the last only after switching off stability control), which alter the all-wheel-drive system, the rear-wheel steering, the limited-slip differential, and the stability control. There’s also a launch mode; the only thing missing is the C63’s Drift mode. The driver can load two of the selectable elements onto the steering wheel’s left display circle, where two buttons allow one to cycle through the choices without delving into the touchscreen.

To wring the very most out of the powertrain, it’s necessary to load Boost mode onto that left circle; available when in Race mode only, it allows the electric motor to deliver its maximum 201 horsepower in 10-second bursts.

One of the previously unknown GLC63 experiences, evidently, is motorsports driving. There’s also a Drag Race menu, should you be headed to the Christmas tree. Or if you’re on a road course, the GLC63 has saved maps of major racetracks. For your track session, you can record and later download telemetry including speed; steering wheel angle; longitudinal, lateral, and vertical acceleration; slip angle; front and rear wheel angle; boost pressure; electric turbocharger power; engine output, torque, and speed; gear engine or transmission oil temperature, 12V battery voltage and current, HV battery charge level, voltage, current, and temperature; rear axle locking ratio; individual tire temperatures and pressures; and on and on—80 parameters in all. Is anyone going to use this? “We don’t know how many of our customers are going to a racetrack,” admits AMG product planner Patrick Roth. But “if you want to, you can do it.”

At the far opposite end of the spectrum, there’s the electric-driving component. The GLC63 can be driven in EV mode, and the motor is muscular enough for highway speeds, although pushing through the accelerator’s kick-down detent will wake the gas engine. EV range is only a few miles (12 kilometers on the European WLTP cycle, which equates to about six miles using EPA methodology), so if you’re keen on battery-electric driving, this really isn’t your car.

The GLC63 does offer four levels of liftoff regen (from none to one-pedal driving)—but the higher-than-standard levels can’t be selected until the battery is significantly depleted. Once the driver selects a higher-than-standard level of regen, it works in any drive mode except for Race. No matter what liftoff regen level is selected, the brake regen is unaffected, and indeed, brake modulation felt totally natural.

This powertrain’s ludicrous output numbers shade competitors such as the BMW X3 M Competition (503 horsepower, 479 pound-feet) and Alfa Romeo Stelvio Quadrifoglio (505 hp, 443 pound-feet). That certainly sounds like overkill, but the GLC63 has a lot more weight to cart around—some 500 pounds more than the BMW. AMG says the zero-to-62-mph time is 0.3 second better than the old car’s; we got a 3.4-second 60-mph time from the previous GLC63 S, so figure 3.1 seconds for this car. That would just barely nose it ahead of the BMW (3.2 seconds) and the Alfa (3.3). So if the hyper-complicated new propulsion system doesn’t appear to give AMG a major leg up on its rivals, why do it? It’s clear that AMG sees the move as a step toward the EV future. “We’re an engineering company, and we want to develop,” says Roth.

Drive the GLC63 S E Performance, however, and you discover that, for all the over-the-top complexity, this thing just works.

That was the overwhelming feeling we got after two days of driving in southern Spain, mostly along empty mountain roads. Engine response was everything you could ask for and more. As you might guess, the GLC63 also roars off from a stop, without even having to fuss with launch control. Through an extended series of fast sweeping curves and then tighter switchbacks, we switched among the more sporting drive modes. Again and again, the nine-speed automatic delivered well-timed anticipatory downshifts as we dove into corners, held the lower gear for a just-right length of time, and snappily upshifted as our speed climbed.

Out on the highway, flat-foot the accelerator, and acceleration isn’t immediately frenetic. The multi-pronged powertrain takes half a beat to gather itself before shoving the GLC forward on a wave of torque. When cruising, calls for higher speed bring a gentle swell of acceleration with no abrupt downshifts. And in low-speed stop-and-go, the PHEV smoothly hands off between gas and electric propulsion.

Those who are new to AMG should be fully satisfied with this electrified four-banger. Returning buyers, however, may miss the thunderous character of the brand’s V-8s. The turbo four does offer an enhanced sound setting (independent of the drive mode), and while it isn’t bad, it can’t match the deep-throated rumble of the V-8, especially at startup.

The GLC63’s chassis is just as complicated as the powertrain, and here there’s no downside. The steering, in any of the three settings, avoids all the obvious pitfalls—it doesn’t vary wildly in its response and is neither overboosted in Comfort nor overly heavy in Sport+. Instead, it provides predictable reactions and even a modicum of feel. The degree of rear steer depends on the chosen drive mode, among other factors, and there was one point during a series of moderate-speed twisties when we could feel it tightening the line. But during most of our two-day drive, its helping hand remained invisible.

The suspension is especially impressive. A brutal ride is typical of high-performance SUVs (we’re looking at you, X3 M Competition). Not so here. These adaptive dampers are claimed to offer a wider range of compression and rebound tuning, and together with the steel springs they provide impressive bandwidth. The ultra-low-profile tires (Michelin Pilot Sport 4 SUV, 265/40ZR-21 front and 295/35ZR-21 rear) don’t offer much cushion over sharp ridges, but the suspension never feels jarring or stiff-legged. With the standard active anti-roll bars, head toss never rears its, uh, head, and body roll is a nonissue in the cars we drove.

The optional AMG Performance seats, however, are too firmly padded to be truly comfortable. At least they’re not overly confining, although the outer bolsters can be adjusted for a tighter squeeze. The interior is otherwise little changed from the standard GLC and has the same pros and cons as most current MB products. Pros: a sleek waterfall dash that swoops down to the center console, great-looking digital displays, and a central screen that minimizes menu diving. Cons: a total lack of physical switchgear, idiotic touch sliders, and annoying steering-wheel touchpads. Outside, the GLC63 gets the AMG vertical-bar grille and an AMG-specific lower fascia, side sills, and rear diffuser with quad exhaust outlets.

We should also note that the previous GLC63 S was only offered in SUV coupe form; those wanting the more traditional SUV shape had to settle for the mere GLC63. This time around, the SUV version is not held back—we expect the still-to-be-unveiled SUV coupe model, which should appear sometime before the GLC63’s on-sale date in mid-2024, will offer the same powertrain. So that, at least, is simple. Even if not much else here is.