At the XK's heart is Jaguar's latest 300 hp 4.2-liter, 32-valve aluminum AJ-V8. In the XKR, an Eaton supercharger is added, increasing horsepower to 420 and propelling the Coupe from 0-60 in 4.9 seconds. This engine defines power, just as the silky 6-speed ZF sequential-shift transmission allowing gear changes via steering wheel-mounted paddles - characterizes control.