Mercedes-AMG C63 S E Performance review

It’s a regrettably familiar situation. And yet only at the moment that you experience how directly it impacts upon the dynamic appeal of such a unique driver’s car as this one can you really appreciate what its true cost is going to feel like. This is no nicer to report than it must be to read, but an AMG saloon - specifically this one - without a V8 engine seems a strangely bereft thing, like a watch face without hands.

The new Mercedes-AMG C63 S E-Performance has had all manner of powertrain, chassis and steering technologies thrown at it in order to cover for what’s been taken away, of course – and we’ll get to those. The fact is none of them really succeeds at it. And the hardest thing of all to accept is how pointless and churlish it is to complain. The times in which we’re living are those in which a company like Mercedes-AMG can only take drastic action in order to keep cars like this on sale. Frankly, the ones making the biggest changes, and taking the biggest risks, ought to get the loudest applause – provided they’re the right risks.

The C63 S E Performance uses an updated version of AMG’s M139 turbo four-pot, which, in other states of dress, powers the Affalterbach brand’s smaller transverse-engined models. Here, however, it’s fed by a turbocharger the size of a fruit bowl. 

That turbo is driven by a 400V electric motor, rather than just by exhaust gases, in order to eliminate any turbo lag. It helps to produce 469bhp and 402lb ft of combustive power from just under 2.0 litres of swept capacity, which is then channelled through AMG’s nine-speed Speedshift MCT automatic gearbox, and then to the road via a torque-vectoring four-wheel drive system with a rear-mounted electronically controlled limited-slip differential. So as well as going four-cylinder turbo, the C63 has also gone four-wheel drive for the first time. Oh, and there’s four-wheel steering as well. What more could you possibly want?

Well, in this C63, there is more. An electric motor drives straight into the car’s rear differential, via a two-speed transmission all of its own. The P3 performance hybrid system is the same driveline that’s used by the larger GT 63 S and S63 E Performance. In this case, it means the powertrain controllers can blend up to 201bhp and 236lb ft of additional electric grunt with what’s coming down the driveshaft from the piston engine, but they can also power the car electrically for about eight miles.

The drive battery is Mercedes-AMG’s own development. While it’s only small by the standards of most luxury PHEVs (6.1kWh), its construction is specially designed for close thermal management, high energy density and the sort of rapid and intensive supply and storage of energy that’s necessary to prevent a heavy car like this from running out of electrical oomph on track.

It weighs 80kg dry, is carried directly over the rear axle and contains up to 30 litres of coolant, which it distributes around each of the 560 cylindrical cells in the pack. The S63 E Performance uses the same technology in a pack of twice the capacity.

Driving the new C63 on track is a very different experience from the one that the old car traded on so squarely and evocatively. When you’re using Race driving mode, Mercedes-AMG’s Track Precision lap telemetry app logs your position and tells you, via brightly flashing ‘BOOST’ graphics that appear on the car’s digital instrument screen, where best to deploy the better part of the electric motor’s power. It’s the kickdown switch right at the bottom of the accelerator pedal travel that you use to do this, as if it were some Formula 1-grade ‘push to pass’ KERS deployment button. Thusly hooning around, pretending you’re George Russell on a qualifying lap, is certainly fun – and the point is, if you follow the instructions, the C63 won't run out of battery power and should continue to do it almost indefinitely. 

Soon enough, though, you’ll want to know what else your Mercedes super-hybrid has to offer. How much old-school hot-rod charm and dynamic entertainment value have AMG's engineers remembered to include, for example, there to be savoured wherever and whenever you happen to want to tap into it?

Honestly, and compared with AMG's long-standing measure in particular, there isn’t very much - although, when the electric motor’s fully boosting, this is certainly a fast car. Use one of the drive modes other than Race (there are eight in all, counting the Electric and Battery Hold modes associated with the PHEV tech, and not counting Drift mode) and, for the most part, you do get full boost from that electric motor without pushing past the throttle kickdown switch. Lock in a higher gear ratio using the paddles for the nine-speed ’box and the torque that floods in at middling engine revs makes the car feel effortlessly, instantly brisk.

As those revs rise, though, there’s no mistaking what you’re working with. The four-pot just doesn’t rev with the freedom that a bigger multi-cylinder engine would. The car doesn’t stonk on from 5000rpm with quite the ferocity you somehow expect of it, however unreasonably. And, on track at least, it’s a little too easy to run into the car’s rev limiter after a downshift, because the high-rpm power delivery we’ve got used to in a C63 just isn’t there.

Neither is the enticing audible allure of a proper multi-cylinder performance engine, needless to say. The C63’s new four-pot turbo sounds 'all right' - but, to me at least, it certainly doesn’t sound like very nearly £100,000, which is what this car is likely to cost once you've lavished a few options on it.

For handling, the switchable four-wheel drive system does indeed offer some rear-driven track adjustability and amusement factor if you use that secret-handshake-enabled Drift mode. But the rest of the time, the torque vectoring dynamic benefit you’re expecting to feel from the car’s better-balanced weight distribution, and that diff-mounted electric motor, doesn’t ever really materialise. 

The new C63 rides with moderation on the public road and has good body control at faster road speeds, but it begins to jiggle and jounce, and to struggle to rein in its mass, on more testing surfaces. On circuit, you feel the impact of the car’s 2.1-tonne kerb weight in a tendency to push into gentle but persistent understeer through faster sweeping bends - and in a perceptible reluctance to shed speed in harder braking areas.

The C63 feels like a large and heavy car now, because that's what it has become. That’s the plain truth. The extra dose of grip and agility that its predecessors offered relative to their bigger super-saloon siblings is gone. Want to hoof the rear axle into the sort of long, indulgent powerslide that so many C63s have felt made to do? Unless you’re in Drift mode, forget it. 

But the loss of so much rich and demonstrative charm in this car overarching character is a much greater one than anything to do with its weight, or its handling. That’s the loss that the engineers will be powerless to mitigate over time, that advancing battery technology can do nothing to help.