Mercedes AMG Raises the Bar With New GT R

BROOKLANDS, U.K. – Mercedes-Benz’s AMG performance-car offshoot lifts the veil on its most advanced road model to date – the 585-hp 4.0L turbocharged V8-powered GT R.

Revealed at a media presentation here as part of this year’s Goodwood Festival of Speed activities, the new range-topping Mercedes-AMG GT model is billed as a road-going version of the German automaker’s 2016 Nurburgring 24-hour race-winning GT3, from which it borrows a number of key racetrack-inspired components, including an adjustable aerodynamic package and coilover suspension system.

The ’18 GT R goes on sale in November, although North American deliveries are not planned until mid-2017. Pricing has yet to be announced, although officials suggest it will come at a handsome premium over the GT S at around $200,000.

Contrary to earlier speculation, production of the latest member of the GT lineup will not be limited. Rather, volume will be driven by demand, which AMG indicates already was strong ahead of its unveiling here.

“With the GT R, we have reached the next level of driving performance. It combines the driving dynamics of our latest GT3 racing car with the everyday practicality of the standard GT,” says Tobias Moers, CEO of Mercedes-AMG. “We have modified all the performance relevant components and linked them together intelligently.”

The rear-wheel-drive GT R runs the most powerful version of Mercedes-AMG’s M177 engine yet. The 4.0L direct-injection gasoline unit receives new turbochargers featuring an altered machining process for reduced frictional losses and modified wastegates for added efficiency.

As part of a reworked engine-mapping program, it also operates with an added 0.15 bar of maximum boost pressure at 1.35 bar as well as a higher compression ratio than existing variants of the V-8.   

AMG says further changes have been concentrated on the exhaust ports, combustion process and flywheel – the latter of which is described as being 1.5 lbs. (0.7 kg) lighter than that used by the GT S, giving it what Moers describes as added throttle response, enhanced load change characteristics and a more linear delivery.

With 585 hp at 6,250 rpm, the M177 engine delivers 75 hp more than the less heavily tuned version used by the GT S. Torque rises by 37 lb.-ft. (50 Nm), swelling to a new peak of 516 lb.-ft. (700 Nm) on a 600-rpm-wider band of revs between 1,900 and 5,500 rpm. 

By comparison, the Porsche 911 GT3 RS, a car AMG engineers admit was benchmarked extensively during the development of the GT R, uses a naturally aspirated 4.0L horizontally opposed 6-cyl. engine with 500 hp at 8,250 rpm and comparatively meager 339 lb.-ft. (460 Nm) of torque at a high 6,250 rpm.

To make the most of the added performance, Mercedes-AMG brings a number of newly developed components to the GT R, including a unique carbon-fiber torque tube that is claimed to be 40% lighter than that used by the GT S at 31 lbs. (14 kg) as well as standard-fit forged aluminum wheels and a titanium rear silencer. There also is a standard carbon-fiber roof, less sound-deadening material within the floorpan structure and a less heavily specified interior than earlier incarnations of the AMG coupe.  

The result is a 33-lb. (15-kg) reduction in curb weight over the GT S at 3,428 lbs. (1,555 kg). In combination with 14.7% bump in power, this serves to provide the GT R with a better weight-to-power ratio than the GT S and 911 GT3 RS.

Allied to the reworked engine is a revised 7-speed dual-clutch AMG Speedshift gearbox. It receives a longer first gear ratio together with a shorter seventh gear. The final ratio also is shortened, and altered mapping is claimed to make the race-start function even more aggressive through an increase in the amount of revs it accepts prior to engaging.   

With an official 0-62 mph (0-100 km/h) time of 3.6 seconds, the GT R is 0.2 seconds faster up the strip than the GT S. Yet despite claims of added traction brought on by a uniquely tuned electronic limited-slip differential, wider rear track and standard 20-in. rear wheels shod with 325/30 profile Michelin Pilot Sport Cup 2 tires, it can’t quite match the out-of-the-blocks explosiveness of the 911 GT3 RS, which boasts an official 0-62 mph time of 3.3 seconds.

The lift in performance over the GT S has necessitated changes to the cooling and aerodynamic properties of the standard GT. Included among the tweaks to the exterior, including the adoption of a co-called Panamericana grille treatment from the GT3 race car that AMG suggests will become a key design element on future AMG models, is an active diffuser element mounted within the underbody that motors forward by 1.6 ins. (41 mm) at speeds above 50 mph (80 km/h) in race mode to reduce front-axle lift a claimed 88 lbs. (40 kg) at a speed of 155 mph (249 km/h).

AMG also fits the GT R with an adjustable rear wing fashioned out of carbon fiber. Mounted on the liftback-style tailgate, it combines with newly pressed body sides that widen the rear fenders 1.1 in. (28 mm) each side to deliver an added 342 lbs. (155 kg) of downforce at the new car’s claimed 198 mph (319 km/h) top speed.

Despite the additional aerodynamic features, AMG says the GT R boasts a lower drag coefficient than the GT S. This is reflected in its top speed, which is 4 mph (6 km/h) up on the GT S despite the adoption of shorter seventh gear and final-drive ratios.

At the heart of efforts to endow the GT R with the handling prowess to match its rabid performance, AMG has fitted it with a new carbon-fiber cross tunnel. Mounted under the exhaust and torque tube, it is claimed to increase torsional stiffness 7.5% over the GT S. A new carbon-fiber engine brace helps stiffen the front end.

Underpinning the new AMG flagship is a heavily reworked double-wishbone suspension featuring a number of solutions originally developed for the Nurburgring 24-hour-race-winning GT3. It boasts coilover spring/damper units allowing adjustment to the spring rates, which in turn influences the drive and roll behavior. An AMG Dynamic Select function provides the choice of comfort, sport and sport plus damping characteristics.

Up front, the wishbones, steering knuckles and hub carriers are manufactured out of forged aluminum to reduce unsprung mass. AMG also fits new uniball bearings to the rear wishbones to provide greater toe-in and camber control than with standard bushings.    

The biggest change to the chassis, however, is reserved for the steering. Together with variable-ratio speed-sensitive front steering, the GT R is the first Mercedes-AMG model to adopt rear steering.

At speeds up to 62 mph, the rear wheels are turned in the opposite direction of those at the front, leading to a virtual shortening of the wheelbase for added maneuverability and agility. Above 62 mph, the rear wheels turn in the same direction as the front wheels for a virtual lengthening of the wheelbase with added steering response and stability. Two electro-mechanical motors are used to provide the steering effect at the rear up to a fairly conservative angle of 1.5 degrees.

In light of the various changes to the chassis, AMG claims a 47:53 front-to-rear weight distribution. Alongside the standard steel brake package, which uses vented and perforated 15.4-in. (391-mm) front and 14.2-in. (361-mm) rear discs, buyers can opt for optional carbon-ceramic brakes with 15.8-in. (401-mm) front and 14.2-in. rear composite discs, a move that trims 37 lbs. (17 kg) from the curb weight.

In deference to the development program of the GT R, which centered heavily on the notoriously demanding Nurburgring Nordschiefe circuit in Germany, otherwise known as the green hell, AMG unveils the new car in an exclusive color known as “Green Hell Magno.”

The GT R is to be followed by an even more aggressively tuned GT Black Series model, details of which AMG is yet to make public.