ROAD TEST: MERC-AMG GT63 4-DOOR COUPE

Mercedes-amg branches out with a four-seat grand tourer with bruising performance

The past decade has been one of real developmental significance for Mercedes-amg. The firm’s continuing ability to transform practically any of Mercedes’ relatively ordinary cars into bona fide road and track performance weapons – often to class-leading effect – continues to be the foundation of its success. Meanwhile, the brand’s association with a certain five-time Formula 1 world champion and his Amgliveried racing car must also have played its part.

Arguably of even greater significance than both, though, is the fact that, within the past 10 years, Mercedes-amg has turned its hand to developing its very own sports cars. The SLS was the first such creation, first appearing in 2009 with its dramatic 300Sl-style gullwing doors and naturally aspirated 6.2 V8 – and its successor, the Mercedesamg GT, arrived in 2014 to continue the two-seater sporting theme. Neither was derived from an existing Mercedes model; both were intended to represent the wider reaches of what Affalterbach can achieve when presented with a blank canvas and a generous R&D budget; and both have proved good enough to convince Mercedes’ top brass that AMG should even be involved in the engineering of non-amg car lines.

However, AMG’S third in-house model, and subject of this week’s road test, is a different kettle of fish for several reasons. Welcome, then, to the imposing of stature and convoluted of name Mercedes-amg GT 4-Door Coupé, a four-seat sporting GT designed to leave more than a whiff of Affalterbach on the turf of cars as different as the Porsche Panamera and Bentley Continental GT.

Being AMG’S first stand-alone model with four seats, this car should broaden the company’s model portfolio quite a bit – but if it’s a proper GT car, it’ll be necessarily different from the SLS and GT that have preceded it. Read on to find out exactly how different that means. DESIGN AND ENGINEERING The arsenal of technology required to make a 5.05m-long, 2.1-tonne car handle like a smaller, lighter, lowerslung sports car takes some wrapping your head around. The GT 4-Door Coupé does without the lightweight spaceframe construction of its twodoor 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. 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 fourseater 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.

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; fourwheel 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.

INTERIOR

The GT 4-Door’s interior is, in fairly large part, what you’ll find in a generously equipped version of the CLS, but for a raised centre console and some detail and trim differences.

The door panels arch elegantly inwards to meet a dashboard dotted with Mercedes’ hallmark turbine air vents, and behind the busy spokes of a new multi-function steering wheel sits a 12.3in digital instrument binnacle ‘dual bonded’ to another, more central display of identical size. AMG might have done more to distance its latest ware from that of other Mercedes and AMG models, but the overall effect is convincing: sumptuously old world in part but simultaneously very cutting edge.

Less convincing is the fascia on the transmission tunnel, which is one of the few interior elements bespoke to the four-door GT. It’s inspired by the GT two-seater’s centre console and features the same embossed gearlever, but it seems a touch ugly

and quite space-inefficient. There’s a broader point here: that while material quality is mostly excellent and the nappa leather conspicuously soft, switchgear remains an area in which Mercedes still trails the likes of Porsche and Bentley, whose fitments feel more robust and have a more tangible sense of perceived quality.

In the rear of the cabin, Mercedes’ steeply raked roofline eats into head room for taller passengers a little, although leg room is generous and the seats themselves comfortable. To accommodate three abreast, you’ll need to tick an option box, because as standard the GT63 comes without a central berth – or the ability to fold the asymmetric seatbacks down and increase the capacity of the car’s 461-litre boot.

The boot itself is an adequately commodious space big enough to carry four good-sized duffel bags, although a Panamera Sport Turismo would carry five and an M5 saloon perhaps six. As with all fastbacks, the opening is uniformly broad, although the lip is also stubbornly deep.

PERFORMANCE

AMG chief Tobias Moers says this 4.0-litre engine is now nearing the limit of its performance potential. Handily for him, on the basis of this road test – in the lesser of two available derivatives, let’s not forget – you have to question how much more power a four-door performance car could ever sensibly need.

With the car’s launch control

Panamericana grille dominates the GT63’S low, wide front end, lending the dramatic four-door coupé spades of presence. The outline shape is similar to that of a Mercedes CLS, but that car has the biplane wing design instead of the vertical chrome bars here.

These painted 20in alloy wheels are standard fit on the GT63. The GT63 S gets a different, multi-spoke 20in rim as standard. Forged 21in wheels are available as an option on either car, though, upping the section of the rear tyres to a whopping 315mm.

The rear spoiler forms part of the GT63’S active aerodynamics package and it extends and retracts depending on speed. There are louvres in the lower front apron of the vehicle, too, which open and close to optimise airflow.

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

SLS was AMG’S first stand-alone model

Boot space is good for an outright performance car but less impressive for a fourdoor family conveyance. The lip is also unusually high, which could hinder loading.

Steering wheel is slightly offset but the driving position is low and supportive, with plenty of space and adjustability in the steering column. It feels purposeful.

A central rear seat is an option. Our test car’s two back seats were comfortably sculpted; a little restrictive in terms of head room, but only for those over 6ft 3in.