Mercedes-AMG has also focused on lightening the GT R. To that end, it has forged 20in aluminium wheels and a titanium silencer. There is also a carbonfibre roof, less sound deadening material and less equipment. This all gives the car a power-to- weight ratio of 371bhp per tonne.
The GT’s AMG Speed-shift seven-speed dual-clutch automatic gearbox has also been fettled with a longer first gear ratio and a shorter top gear. The final drive ratio has also been shortened and the Race start function made even more aggressive.
Its official 0-62mph time is 3.6sec, 0.2sec faster than the GT S. Yet despite claims of added traction brought from the uniquely tuned electronic limited-slip diff, wider rear track and 325/30 Michelin Pilot Sport Cup 2 tyres, it can’t quite match its main rival, the Porsche 911 GT3 RS, which does the sprint in 3.3sec.
A whole series of changes to the exterior styling includes the adoption of a co-called Panamericana grille from the GT3 that is set to become a key design element on future AMG models. There’s also an active diffuser element mounted within the underbody that motors forward by 40mm above 50mph in Race mode; it is claimed to reduce front axle lift by 40kg at 155mph.
AMG has also fitted the GT R with a carbonfibre rear wing that combines with the wider body to give an added 155kg of downforce at 198mph.
Despite the additional aerodynamic addenda, AMG says the GT R has a lower drag coefficient than the GT S. This is reflected in its 198mph top speed, which is 4mph up on the GT S despite the shorter top gear and final drive.
In a bid to give the GT R the handling prowess to match its rabid performance, AMG has fitted it with a new carbonfibre cross-member that’s mounted under the exhaust and new carbonfibre torque tube and is claimed to increase torsional stiffness by 7.5% over the GT S. There is also a carbonfibre engine brace to stiffen up the front end.
Underpinning the new AMG flagship is a heavily reworked double wishbone suspension system developed from that of the GT3 racer. A so-called AMG Dynamic Select function provides a choice of three damping characteristics: Comfort, Sport and Sport Plus.
Up front, the wishbones, steering knuckles and hub carriers are manufactured out of forged aluminium in a move that provides a reduction in unsprung masses. AMG has also fitted new uniball bearings to the rear wishbones to provide greater toe-in and camber control than with the standard bushings.