Redefining Supercar Performance
Germans are not typically given to hyperbole. But when Tobias Moers, the head of Mercedes-Benz’s AMG division, says about the Mercedes-AMG GT R, “We put everything into this car. We invested all our heart and soul into it…” you better sit up and pay attention! That’s because the AMG Petronas Formula One team has dominated F1—the pinnacle of motorsports—for three seasons, winning 51 of 59 races and earning three driver and manufacturer championships. Mercedes-Benz has made it clear that they are in motorsports to expand their corporation’s technical and engineering knowledge and then apply what they have learned to the cars they sell. Nowhere is that more apparent than with the soon-to-be-released Mercedes-AMG GT R, a Mercedes-Benz they call “a track car off the showroom floor.”
Unique to the AMG brand are handmade “One Man – One Engine” (signed by the craftsman who built it) power plants. The new Mercedes-AMG GT R boasts a 4.0-liter, twin-turbo V8-rated 577-hp at 6,250 rpm. More impressive is the 516 lb-ft of torque that it makes between 1,900 and 5,500 rpm. While horsepower figures make the headlines, torque—especially torque this strong coming on at such low engine rpm—is what gives that satisfying push you feel in your back when you press down on the accelerator. Torque, every racecar driver will tell you, is your friend!
An engineering trick AMG learned from Formula One is where best to bolt the turbochargers for maximum efficiency. Rather than placing them outside of the cylinder banks, they have been located within the “V”. Engineers call this an “inside hot V” design. AMG claims, “The benefits are: a compact engine design, instantaneous response from the turbochargers—free from turbo lag—and low exhaust gas emissions thanks to optimum air flow for the close-coupled catalytic converters.”
Although the car’s motor is in front of the driver, AMG describes the GT R as front-mid engine. Placing the engine farther back and lower in the chassis results in a slight rearward weight bias, approximately 47% front and 53% rear. With less weight on the front wheels, this scheme gives the car more nimble handling, and with a little more weight out back, the rear tires have more traction. That’s win/win!
Another race-bred design feature is the transmission. It’s a seven-speed, dual-clutch, automated manual design. The driver has the option of selecting one of several modes: Comfort, Sport, Sport Plus, Individual and Race. Each varies the way the computer-controlled transmission shifts based on whether it is being driven on a racetrack or the street. Of course, there is also a pure manual mode allowing the driver to shift gears using racecar-like behind-the-steering-wheel paddles. To help further improve overall weight balance, the transmission is located between the rear wheels.
AMG has added several design features perfected on the track to help get all of the GT R’s power to the road. The most innovative is electronic limited slip differential and the availability of nine levels of rear-axle traction control. Using a rotary switch on the center console, the driver can select the grip level desired given the road or track conditions. Level 1 is programmed to deal with reduced grip conditions such as rain. This adds a level of safety reserve by allowing minimal slip of the tires. At the other end of the spectrum, Level 9 allows for maximum slip. During acceleration, when the wheels reach the driver-programmed level of slip, traction control modulates the engine output so that this level is not exceeded and the vehicle continues accelerating. The effect of the electronic limited-slip differential—a technology that ensures power is sent to both rear wheels—is also included in the adjustments. AMG claims that all of this computer-controlled magic takes place without lag. They say it not only improves the grip of the driven wheels, but also increases cornering speeds at the limit.
While the engine and transmission have been designed to deliver maximum acceleration, the Mercedes-AMG GT R would certainly be less exciting to drive without superior handling performance to match. AMG has that covered, too. Dipping into their racecar bag of tools, the engineers have built a suspension that mirrors what they use on the track in their AMG GT3 customer sport and the German Touring Car Masters Series cars. First, wishbones, steering knuckles and hub carriers on the front and rear axles are manufactured entirely out of forged aluminum in order to reduce the unsprung weight. Racing experts know that excessive unsprung weight worsens wheel control under hard acceleration or braking. The double-wishbone design plants the wheel firmly with minimal flexing. Because this results in high camber and toe-in stability, the driver is provided with the potential for fast speeds and excellent road feel when cornering at the limit.
The designers also learned the unique qualities and adjustability of a suspension design called coil-over. As in professional motorsport, a coil-over design gives drivers the ability to select their personal setup and infinitely adjust the spring preload. This makes it possible to set the amount of dive experienced on heavy braking and body roll in hard cornering. Essentially, the driver can tailor the grip of the Mercedes-AMG GT R precisely to what’s required, be it personal preferences or the characteristics of a particular racetrack.
The GT R’s coil-over suspension is combined with a system called AMG RIDE CONTROL, which makes the suspension a continually variable and adaptive damping system. Everything is computer controlled and automatically adapts the shock absorber damping to the current handling situation, speed and road conditions. Damping is modulated rapidly and precisely by separate valves for rebound (downward) and compression (upward) in the shock absorbers.
One last thing about suspension: as standard equipment, a first-in-an-AMG active rear-wheel steering system has been installed. This provides an ideal combination of agility and stability, handling characteristics normally in direct conflict. This by-wire system adjusts the angle of the rear wheels within a predefined operating map. Up to a speed of 62 mph, the rear wheels are turned in the opposite direction to the front wheels. In effect, this shortens the wheelbase, making the Mercedes-AMG GT R more agile. A side benefit is greater driving enjoyment and less steering effort, especially on small and winding roads, narrow racetracks and slalom or autocross courses. Further benefits include increased maneuverability and a smaller turning circle in everyday driving situations, especially helpful when parking. Naturally, all of this happens without driver intervention.
This brief article can only touch on the impressive technical achievements AMG has built into the new GT R. From aerodynamic tweaks that improve top speed stability to fade-resistant race-inspired brakes, this car will make a drive to work or around a racetrack a memorable experience. Cossetted in racecar-like, supportive bucket seats surrounded by carbon-fiber accents and, more important, carbon-fiber components that add strength while removing performance-robbing weight, the driver will be confident that he or she has one of the most exciting automobiles in the world. If you’re still not convinced, here’s one more interesting tidbit: the Mercedes-AMG GT R just set the fastest-ever lap time on the Nürburgring Nordschleife in a test drive independently conducted by the magazine Sport Auto. In a time of 7:10.9, it was faster through the Green Hell—nickname for the 12.9-mile track given by F1 champ Sir Jackie Stewart—than any other roadgoing sportscar ever tested by the motoring magazine.