AMG has long been synonymous with the V8 engine, captivating enthusiasts with the raw energy of high displacement and distinctive, baleful vocals that could almost justify their prices single-handedly. However, the latest versions of the C63 and GLC63 have bucked that trend, ditching their celebrated V8 for a four-cylinder hybrid. What gives? 

Well, things are rosier than they seem, but the GLC63 is also a complex labyrinth of tech that requires patience and experimentation to fully comprehend. You see, this is no ordinary four-cylinder engine. It is based on the hand-built M139 from the CLA45 S, the most powerful series-production four-cylinder on the market. AMG has enhanced it by incorporating an electric exhaust-gas turbocharger derived from its Formula 1 program. 

This innovative e-turbo uses a small electric motor to spool up before the exhaust gases flow in, effectively eliminating lag and improving power delivery. It operates like the MGU-H (Motor Generator Unit – Heat) found in current F1 cars, but without the ‘Generator’ function. That’s left to the 150 kW rear-mounted electric motor coupled with a 2-speed transmission, which can send power to both axles, as well as harvest braking kinetic energy to recharge the battery, much like the MGU-K unit that’s also used in F1.

This new M139l engine is supported by a 6.1 kWh lithium-ion battery operating on a 400-volt system that was co-developed with High Performance Powertrains (HPP), the same team responsible for the Mercedes Formula 1 power unit. Leveraging their expertise, HPP designed the battery to be high-density and lightweight while incorporating motorsport-level cooling. However, this hybrid configuration prioritizes performance over fuel economy, resulting in a limited electric-only driving range of just 14 km. In contrast, the GLC43 uses a much smaller e-turbo and an electric motor powered by a 48-volt system instead of the 400 volts used in the GLC63.

Gas in the front, electric in the rear – sound complicated? Well, it is, and having a name as confusing as Mercedes-AMG GLC 63 S E Performance means it’s a greatly misunderstood road-going application of F1 technology. AMG has defied its conventional standards to unlock this higher realm of performance and the headlining figures make it much easier to digest: 671 hp, 752 lb-ft, and a 0-100 km/h time of 3.5 seconds, three-tenths quicker than the GLC63 it replaces, and enough to outsprint its entire cohort: BMW X3 M Competition (3.8s), Maserati Grecale Trofeo (3.8s), Jaguar F-Pace SVR (4.0s), and the Alfa Romeo Stelvio Quadrifoglio (3.8s).

The GLC63 is even quicker than other PHEV performance vehicles like the BMW M5 Touring (3.6s), but, as its Bavarian rival would understand, those electronics are heavy, resulting in the AMG’s curb weight of 2,310kg, the same as a Range Rover Sport. But if they’ve already come this far, why didn’t AMG just use the V8 hybrid setup that’s currently applied in the S63 E Performance and GT63 E Performance? Perhaps it wouldn’t fit into the GLC’s more compact platform, but it would have also remedied any concerns about a downsized engine.

Malevolent, thunderous tones have been replaced by the gravelly, gritty noises of a four-cylinder. The GLC63 doesn’t try to hide the fact that it sounds exactly like the CLA45, especially at full song when the needle bounces off the 7,000 rpm limiter and delivers maximum sonic impact. It is still a pleasing anthem, but one often associated with hot hatches and modified economy cars. The GLC now has a pesky soft limiter too, so you can’t flex your four-cylinder like you could with the outgoing V8s – perhaps for the best. 

While it may not possess the raw energy of its V8-powered predecessors, we can’t deny its effectiveness at extracting performance and unleashing speed. AMG has thrown everything at it: adaptive suspension, rear-wheel steering, active anti-roll bars, dynamic engine mounts with magnetorheological fluid, and even eight selectable driving modes. The all-wheel drive system can send up to 100% of torque to the rear wheels, and the rear electric motor also acts as a virtual limited-slip differential, optimizing torque distribution between the two rear wheels for better cornering.

The result is hysterical point-to-point pace. Turbo lag is virtually non-existent, and the powertrain packs tremendous low-end thrust as if you’ve just engaged the afterburner, transmitting mild vibrations to the cabin for that racecar experience. Foot to the floor, the GLC63 accelerates as outrageously as the numbers suggest, and while the top end is worth seeking out, we find ourselves drawn to the generous mid-range, where torque feels everlasting. Hilariously enough, we then realized that we were only utilizing 80% of the power.

You see, BMW often faces criticism for its extensive array of driving modes and settings, but AMG is no different. It’s just been presented in a more beginner-friendly format with less confusing nomenclature. It’s here that we discovered a feature called Boost Strategy, which is similar to a setting that F1 drivers adjust on their steering wheel. This feature tells the rear electric motor to deliver maximum output for up to 10 seconds. Initially, when we activated Boost Mode using the steering wheel, we didn’t notice any difference. However, upon consulting the manual, we learned that the feature only activates when the gas pedal is pressed beyond the initial stopping point, known as the kickdown point. This action engages a secondary switch, unlocking the full 100%, and the supplemental speed is significant, like having your own pedal-activated DRS button. We thought the GLC63 was quick before. Now, it’s straight up biblical. 

If you find yourself on a racetrack, the Track Pace app will choose the best Boost Strategy for you and indicate when to activate the kickdown to maximize electric boost and battery charge. However, we would prefer a more accessible button on the steering wheel, instead of needing to modulate your foot on the kickdown switch, which does require some practice.

All of this may seem foreign or artificial at first, but as you explore the settings and experiment with different handling and ride options, you gain a deeper understanding and appreciation of what AMG is trying to offer. This experience mirrors what F1 drivers must manage during a race, such as battery charge, boost strategy, tire life, and brake temperature. But suppose AMG had included a steering wheel with more buttons and dials similar to those on the Mercedes F1 wheel. In that case, it would have further emphasized the connection between the two and possibly resonated better with their consumers.

The GLC63 is not only impressive on the straights, but it can carry ridiculous lateral loads into corners yet remain completely flat and grounded. This is primarily due to the optional but highly recommended AMG Active Ride Control ($4,600), which acts as an active roll stabilizer. It reduces body roll, enhances ride quality, and sharpens handling and damping during cornering. Porsche uses similar technology called PDCC, and the difference on the road is palpable.

At low speeds, the GLC63 doesn’t feel its weight, changing directions on a dime with faithful front-end bite and an accommodating yaw on throttle lift. It scythes around corners as quickly as a rear-engined Porsche 911 thanks to light yet articulate steering, but it’s only when you begin to pile on the speed and experience the weight transfer that you realize and appreciate how much mass is being handled electronically. The GLC63 excels at minimizing pitching and rolling, providing a more composed and comfortable ride compared to the BMW X3 M. Only sharper bumps are felt in the cabin. On smoother surfaces and when set to Comfort mode, we found the GLC63 to be an acceptable and enjoyable daily driver.

Like other AMG EQ and E Performance models, the brakes are the weakest element, impacting both stopping confidence and pedal feel. Modulating them requires considerable effort and attention, as they exhibit spring-like resistance due to their setup: six-piston calipers bite the front while a single-piston caliper, assisted by the electric motor, handles the rears. This explains the inconsistent pedal feel, making it difficult to brake smoothly and cautiously. Tinkering with the four levels of brake regeneration and a week of acclimatization suppresses but doesn’t entirely remedy our apprehensions about it.

We wish AMG would put more effort into making the GLC63 stand out, as it is hardly distinguishable from the GLC43 from the front. Both models feature the same vertical-slat grille, headlights, and an AMG badge on the hood instead of the traditional Mercedes star. The rear design is also similar, with the GLC63 showcasing rectangular quad exhausts in place of the rounded ones found on the GLC43. Aside from the obvious badging and the “TURBO E Performance” label on the side fender, the only noticeable differences are the wheel designs, since both models share the same paint colours, including this striking Spectral Blue.

Will you trade noise for speed? Many consumers seem hesitant to do so, and AMG has acknowledged these criticisms by planning to phase out this four-cylinder hybrid to return to its V8 roots. It’s unfortunate because the GLC63 is an exceptional technical achievement that simply requires a comprehensive understanding of its avant-garde features to appreciate its capabilities. While it may lack the musical backdrop and grandeur of a conventional AMG V8, its advanced F1 technology cleverly combines mechanical and electronic wizardry to deliver the performance expected from a top-tier AMG. The GLC63 does possess emotional value, but it’s a different kind of thrill, one that’s unfortunately been misunderstood.

Specifications:

Model: 2025 Mercedes-AMG GLC 63 S E Performance SUV
Paint Type: Spectral Blue Metallic
Base Price: $109,500
Price as Tested: $134,350
Wheelbase(mm): 2,888
Length/Width/Height (mm): 4,479 / 1,920 / 1,635
Curb weight (kg): 2,310
Engine: 2.0-litre four-cylinder with electric turbocharger, 6.1 kWh lithium-ion battery, rear-mounted 150 kW electric motor
Horsepower: 671 hp @ 6,750 rpm
Torque: 752 lb-ft @ 5,250–5,500 rpm
Transmission: 9-speed automatic (engine), 2-speed automatic (electric)
Engine & Drive Configuration: Front engine, AWD
Observed Fuel Consumption (L/100km): 13.7
Observed Electric Range: 11 km
Tires: Michelin Pilot Sport 4 SUV; 265/40ZR21 front; 295/35ZR21 rear