Mercedes-AMG GLC 63 S 4Matic review

Mercedes has replaced the familiar 4.0-liter V8 engine with a high-performance Plug-in Hybrid based on an engine with only 4 cylinders. Did the transplant work? Test with the most powerful GLC ever, Mercedes-AMG GLC 63 S 4Matic with 680 PS and 1020 Nm.

Photo: Adrian Barbu

The English have a saying: “No replacement for displacement”, which says very clearly that displacement can’t be replaced by anything. The previous-generation AMG GLC had under the hood the familiar 4.0-liter V8 that developed up to 510 PS and 700 Nm. But a WLTP fuel consumption of 10.7 l/100 km and emissions of 244 g/km CO2 would mean huge emissions penalties today, at least in Europe, so Mercedes, like other manufacturers, had to look for ways to electrify the powertrain while maintaining top performance. The solution is a PHEV propulsion system called the P3 Hybrid. In a nutshell, the technical description is as follows: under the hood works the M139l 2.0-liter turbocharged 4-cylinder engine, longitudinally positioned, supercharged by a turbine electrically driven by a small electric motor only 4 cm in diameter.

The rear axle is powered by a 204 PS electric motor (109 PS continuous output) mated to a two-speed automatic transmission and a limited-lock differential. The electric motor is powered by a 6.1 kWh (4.8 kWh net) battery that charges up to 3.7 kW. The 4-wheel drive system is variable, ranging from 100% rear-wheel drive to 50/50% rear/front. Normally, the electric motor transmits power to the rear axle only, but if the rear wheels tend to spin, the electric motor can also transmit torque to the front via the cardan shaft. There’s also all-wheel steering where the rear wheels steer opposite to the front by 2.5 degrees up to 62 mph (100 kph) and in the same direction as the front wheels by 0.7 degrees above 62 mph (100 kph).

Can the V8 be replaced?

First customer impressions have been unfavorable. Michael Schiebe, AMG’s new boss, says the problem is not the PHEV system but the fact that it’s based on a 4-cylinder engine, and that’s why many customers start with the wrong preconception. What did we feel?

We climb in the AMG seats upholstered in nappa leather with the AMG badge emblazoned on the headrests and grab the AMG Performance steering wheel wrapped in nappa leather and microfiber. We push the start button and start electric mode. 12 km is officially possible with zero emissions, about 9 km in the real world, but it’s not electric range the target of the hybrid system, it’s dynamic performance. There is also a B-mode for conserving battery energy but we do not have a mode for charging the battery using the thermal engine. The battery is charged by recovering braking energy, at the socket with up to 3.7 kW, or with a lower speed when Sport or Sport+ modes are engaged.

The battery is virtually never fully discharged, with around 25% available in almost any situation to power the electric motor. In Comfort mode, the classic steel-spring adaptive suspension delivers a ride comfort that’s enviable for a supersport SUV shod with 21-inch wheels and low-profile tires. You can feel its firm but it elegantly negotiates short bumps without transmitting too much to the interior. There are eight driving modes: Slippery, Individual, B, Electric, Comfort, and three-sport modes – Sport, Sport+, and Track Pace. All modes have nice graphics of the digital instrument cluster with specific informations.

We want to see the sporty side and press the Sport button. The four rectangular tailpipes contribute to a rich, baritone sound that has something of the traditional AMG tone, with rumble on downshifts but without the dramatic intensity of the V8. So, the specific sound is present but not as intense, but at least it’s natural and not artificially generated through speakers.

On start-up, the Mercedes-AMG GLC 63 4Matic accelerates quickly but lacks the punch of the V8 engine, although the electric motor supports the combustion engine from the first moment. On paper, though, the new AMG GLC 63 is quicker: 3.5 seconds compared to 3.8 seconds in the previous V8 model, but that feeling is dampened by the fact that under hard acceleration you immediately feel that only four pistons are working under the hood and the 2.0-liter engine has to push itself hard to accelerate quickly. And it’s a reminder of the British saying ‘no replacement for displacement’.

But the turbo’s response is beyond criticism because the electric turbine eliminates any turbo lag and it accelerates with vigor from the first moment. The 9-speed automatic gearbox shifts smoothly in Comfort and quickly in Sport/Sport+, and the imperfections of other AMG models have been eliminated here thanks to the omnipresent torque and the electric turbine that makes the combustion engine ready for action at any time, regardless of gear.

As the speed increases, the differences with the V8 engine almost disappear. This is really where customers have a bias because it’s hard to see any difference from the old V8 model. But the situation changes when you get past 5,500-6,000 rpm. Here, the 4-cylinder engine lacks the old V8’s typhoon-like explosion. Don’t take this to mean that the PHEV system is sluggish, but it’s not the same feeling as a supersport model, although the electric motor continues to support the combustion engine. The 2-speed automatic gearbox from the electric motor shifts into second gear at 87 mph (140 kph) when reaches the 13,500 rpm rev limit, and the electric engine continues to help propel the car.

With active stabilizer bars powered by motors connected to a 48V network, the supersport SUV hardly leans out of corners at all and masks its enormous 2,310 kg (5,093 lbs) weight very well. Steering that visibly stiffens in Sport and Sport+ modes contributes decisively to the car’s agility and the feeling that the car is lighter than it looks on paper, being incisive without being edgy, linear, and with very good feedback. The AMG composite-disc braking system with 6-piston brake calipers and 396 mm front disks feels very powerful but in the initial stages, the braking feels undersized due to the nonlinearity caused by the switch from regenerative braking to hydraulic braking.

But the 124,236 euros price tag is a bit steep when you consider that it’s 35,000 euros more than the AMG GLC 43 4Matic. When compared to the competition, a BMW X4M with the M Competition package with 510 PS and a more noble inline-6 engine comes in at 107,300 euros, almost 17,000 euros cheaper.