Mercedes-AMG GT review, test drive

 

The all-new Mercedes-AMG GT is the second production model to be conceived, engineered and developed at Mercedes-Benz’s AMG performance car division at Affalterbach on the outskirts of Stuttgart in Germany. The indirect successor to the mighty SLS comes in two distinct guises: the standard GT has been launched internationally and the more powerful GT S driven in this review[N1] . It is expected to come to India at the end of 2015. As well as promising sharpened performance properties, the GT also aims to provide added levels of practicality over the significantly more expensive SLS, with which it shares various elements of its floorpan and driveline. Gone are the heavy gullwing doors and the traditional coupé layout, though. They are replaced by frameless front-hinged openings and a fastback body design with a large tailgate that opens up to reveal a 350-litre boot.  

 

What remains of the first bespoke production model from Mercedes-AMG are the exaggerated proportions and vaguely retro aesthetic appeal, albeit in a more compact package. At 4546mm in length, 1939mm in width and 1289mm in height, the GT is 92mm shorter, the same width and some 27mm taller than the SLS, with which it shares key elements of its aluminium body structure. It also rides on a platform with a 50mm shorter wheelbase, at 2630mm, as well as tracks that are reduced by 2mm at the front at 1682mm and by 1mm at the rear at 1652mm. Eschewing the naturally aspirated 6.2-litre V8 multi-point injected petrol engine of the SLS, the GT is the first Mercedes-AMG model to adopt an advanced new twin-turbocharged 4.0-litre V8 direct injection petrol powerplant mounted well back in the engine bay for optimal weight distribution and low polar inertia – both crucial to top-notch handling properties. Loosely related to the 2.0-litre in-line four-cylinder direct injection petrol engine used in the AMG version of the CLA and GLA.  The 90-degree unit features turbochargers mounted inside the cylinder banks – a layout AMG claims boosts thermal efficiency, provides optimal throttle response and reduces emissions whilst providing for compact packaging.

 

Further highlights of the new engine, which was developed in-house and goes under the internal codename M178, include dry sump lubrication to better withstand cornering forces, and an exhaust system with fully variable exhaust flaps that allows the driver to vary the intensity of the engine's sound via a button on the centre console. The results look compelling on paper. The new V8 provides the standard GT with 456bhp at 6000rpm and 61.10kgm of torque between 1600rpm and 5000rpm. With added turbocharger boost pressure, output rises to 503bhp at 6250rpm and 66.22kgm  from 1750-4750rpm in the GT S. By comparison, the standard SLS offered up 563bhp at 6800rpm and 66.22kgm  of torque at 4700rpm. The car the GT S is really aiming at in pure performance terms, though, is the Porsche 911 Turbo. In its latest incarnation, the Porsche's twin-turbocharged 3.8-litre horizontally-opposed six-cylinder engine serves up 513bhp at 6000rpm and 67.33kgm at 1950rpm.

 

Channeling the heady reserves to the rear wheels is a revised version of the dual-clutch gearbox originally engineered by German specialist Getrag for the SLS. Mounted at the rear in a classic transaxle layout, the compact unit helps to provide the new Mercedes-AMG model with a claimed 47 percent front and 53 percent rear weight distribution. The seven-speed transaxle gearbox has been heavily upgraded with a new electronic package that sees it offer up to five different operational modes: Controlled Efficiency, Sport, Sport Plus, Individual and, on the GT S only, Race. Further functions include automatic stop/start, brake energy recuperation and a coasting function that idles the engine on a trailing throttle in Controlled Efficiency mode.  Both GT models receive a standard locking differential, but whereas the standard GT gets a traditional mechanical unit, the GT S is fitted with an electronic function that is claimed to provide greater levels of traction by constantly varying the locking effect in acceleration and overrun.  The GT is based around a magnesium and aluminium body structure produced by German construction specialist Thyssen Krupp – the same company that turns out body structure components for McLaren and Lamborghini. In standard GT guise, the new AMG performance flagship tips the scales at 1540kg, while the GT S comes in at 1570kg.