Two available variants both use the same all-new twin-turbocharged 4.0-liter V-8 as the one in Mercedes' recent AMG GT sports car. It replaces the naturally-aspirated V-8 in the outgoing models.
It makes 469 horsepower and 479 pound-feet of torque in the base C63, which has a 4-second zero-to-60 mph time, according to the automaker. The C63 S has 503 horsepower and 516 pound-feet of torque and is good for a 3.9-second zero-to-60 mph time.
Both cars will be rear-wheel-drive and come with a seven-speed automatic transmission with paddle shifters. A three-mode adjustable suspension will be standard while an active exhaust system and carbon ceramic brakes will be optional.
The C63 is aimed directly at rival crazy-fast sedans like the BMW M3, Lexus IS, and the ATS-V that Cadillac will unveil at November's L.A. Auto Show. Infiniti has spent much of 2014 touting its Q50 Eau Rouge, a 560-horsepower prototype it's expected to put into production soon.
As with other AMG models, Mercedes wrapped the ferocious engine in a relatively sedate exterior. The front and rear bumpers are a bit more aggressive, a quartet of exhaust pipes poke out the back, and there's subtle badging throughout the car.
Inside, the C63 stocks the same overachieving cabin as the rest of the C-Class, save for some extra buttons to control the AMG-related performance upgrades. Europe also gets a C63 station wagon, but that car isn't headed to the U.S. on account of our small appetite for wagons.
The cars will make their official debut next week at the Paris Motor Show and their North American debut at the L.A. Auto Show in November. They'll storm into Mercedes dealerships in March.