No longer does the BMW M3 rule as king of the sports sedan. Two new challengers have come to dethrone it: The Cadillac ATS-V and the Mercedes-AMG C63 S. The Cadillac was brought up on the Nurburgring with its twin-turbo V6 giving it 40 more HP than the M3 while the Mercedes-AMG sports 503 HP with its own twin-turbo V8.
