This prototype is a two-door version of the Mercedes-Benz S63 AMG, and it will likely arrive next year to replace the current CL63 AMG in Mercedes' high-powered coupe lineup. Our spy photographer caught the S63 AMG coupe testing in Germany and reports that it "sounds great" when driven with vigor.
Clues that this car has been worked over by the AMG wizards of Affalterbach, Germany, include large cross-drilled brakes with massive calipers, gaping air intakes in the lower front fascia, and the snarling exhaust note audible to our spy shooter. As for the car itself, Mercedes already hinted that the CL-Class will soon be replaced with an S-Class coupe, by presenting the Concept S-Class Coupe earlier this month at the 2013 Frankfurt Motor Show. This camouflage test car looks remarkably like that concept, with a long hood, gracefully curving roof, and stubby trunklid topped by an integrated spoiler.
The Mercedes-Benz S63 AMG coupe will use the same powertrain as the new Mercedes-Benz S63 AMG sedan, a twin-turbo 5.5-liter V-8 good for 577 hp and 664 lb-ft of torque. With a seven-speed automatic transmission directing power to the 4Matic all-wheel-drive system, Mercedes says the S63 AMG sedan can hit 60 mph in 3.9 seconds seconds. The forthcoming coupe will, like the sedan, almost certainly be offered only with 4Matic, the better to harness all that torque.
In addition to the Mercedes-Benz S63 AMG, the new S-Class coupe will also be offered in S550 guise; like the 2014 Mercedes-Benz S550 sedan, it will pack a twin-turbo 4.7-liter V-8 with 449 hp and 516 lb-ft. And at a later date, both the coupe and sedan will be offered in S65 AMG guise, with a twin-turbo 6.0-liter V-12 engine that could deliver as much as 621 hp and 738 lb-ft.