The arsenal of technology required to make a 5.05m-long, 2.1-tonne car handle like a smaller, lighter, lower-slung sports car takes some wrapping your head around. The GT 4-Door Coupé does without the lightweight spaceframe construction of its two-door namesake, instead relying on Mercedes’ MRA monocoque car platform – and that’s why it weighs so much, and why there is so much physics for all that tech to overcome.

Our GT63 4Matic+ test subject – the current entry-level derivative for the UK market – is powered by Affalterbach’s 4.0-litre biturbo V8 engine. The ‘hot-vee’ configuration of the motor’s twin turbochargers should be familiar, but the use of so-called ‘anti-friction’ bearings inside those turbochargers is new and helps to sharpen the motor’s responses. In the GT63, the V8 makes a peak 577bhp and 590lb ft, the latter spread from 2500rpm to 5000rpm.

Simon Davis

Simon Davis

Road tester
All V8-engined GT 4-Door Coupés get quad exhausts (Six-cylinder models offered in other markets don’t) and the GT63 is fitted with an AMG performance exhaust system as standard

The upper-level GT63 S 4Matic+ derivative, meanwhile, makes fully 630bhp and 664lb ft. In either case, and true to form, AMG plainly hasn’t risked under-endowing its four-seater debutant. The car deploys its firepower to all four wheels via AMG’s nine-speed multi-clutch transmission (in which a wet clutch in place of a torque converter helps reduce weight and inertia) while an electromechanically controlled clutch rallies torque from the permanently driven rear axle forwards as required.

Find an Autocar car review

Driven this week

The AMG’s suite of cutting-edge drivetrain and chassis technology doesn’t end there. There’s a torque-vectoring, actively locking differential at the rear axle; four-wheel steering as standard; active aerodynamics similar to those found on the GT R coupé; lightweight alloy wheels; and an electromechanical steering rack with a passive variable ratio. A multitude of drive modes and corresponding selectable traction and stability control programs (the latter dubbed AMG Dynamics) are also present to allow the driver to fine-tune the handling to a level that, AMG claims, isn’t possible on its lesser cars.

For suspension, V8-powered GT 4-Doors make use of a pseudo double-wishbone arrangement at the front and a multi-link configuration at the rear, along with air springs and AMG’s Ride Control adaptive dampers. Anti-roll bars derived from those of the GT R help reduce the weight of both axles.

On that subject, however, our fully fuelled GT63 weighed 2135kg on our test scales, with that mass split 54:46 front to rear. For perspective, the front half of it weighed 1155kg – 10kg more than an entire Volkswagen Polo. The BMW M5 we tested last year was almost 200kg lighter. Not the best omen for the car’s handling – but also not one beyond AMG’s established powers to recover from.

Save money on your car insurance

Compare quotesCompare insurance quotes

Find an Autocar car review

Driven this week