Powering the RS7 is a 4.0-liter twin-turbo V8 mustering up 591 hp and 590 lb-ft (800 Nm) of torque that’s coupled to an eight-speed transmission. While that does give the current RS7 a 38 hp and 74 lb-ft (100 Nm) advantage over the previous generation model, it is not quite enough to match the GT 63 S 4-Door.
The Mercedes also uses a twin-turbo 4.0-liter V8, but it delivers an extraordinary 630 hp and 664 lb-ft (900 Nm) of torque and is mated to a nine-speed transmission sending power to all four wheels. Mercedes says the super sedan needs just 3.1 seconds to hit 60 mph (96 km/h), and during these tests, its power advantage was simply too much for the Audi to overcome.
In a drag race, the RS7 and GT 63 S rocket off the line at similar speeds, but after the first 30 feet or so, the Mercedes starts to edge ahead, finishing the quarter-mile in 11.1 seconds compared to the 11.6 seconds needed for the Audi. It is a similar story in a rolling drag race, where the Mercedes and its added grunt prove to be just too much for the Audi to deal with as the beast from Affalterbach accelerates off into the distance.