Jaguar really designed an amazing looking car in the Mark X. Unfortunately its performance was never intended to match its looks. But someone corrected that with this Mark X by installing the complete powertrain from a 1996 Jaguar XJR-6. That means the fully independent suspension, high performance ABS brakes, four-speed automatic transmission and supercharged 4.0L inline-six with 322 horsepower and 378 ft-lbs of torque. The Aston Martin DB7 wheels really finishes off the upgrades.
Source: Hemmings (link no longer works)