Jaguar's new 5.0-litre V8 that sits at the heart of all XKs is a revelation. It’s smooth and eager to rev, and it emits a glorious burble that switches to a snarl at the top of the rev range. Going down the ’box in manual mode, the exhaust even pops and crackles. Brilliant.
In-gear acceleration is sharp. The normally aspirated XK takes 2.5secs to get from 50mph to 70mph. But the linear nature of the power delivery never makes it feel that quick – the old supercharged 4.2-litre V8 XK suddenly unleashed a great gob of acceleration, while the new naturally aspirated XK piles on the speed with less drama.
Opt for the XKR and the supercharged V8 turns what is an extremely good GT into both an excellent and extremely fast one. The engine means that it shoots from 0-60mph in just 4.6sec, but the killer blow is that the XKR fires from 50-70mph in 1.9sec.
If this doesn’t look so impressive on paper, on the road it’s the difference between picking off one overtaking victim and a whole swarm of them. More impressive still is the sheer relentlessness of the acceleration. Maximum torque of 461lb ft is on tap from 2500rpm to 5500rpm, making it hugely tractable. Like the same-engined XF saloon, the XKR is benign and unimposing when you want it to be and demonically quick when you plant your right foot.
The standard XKR is hardly lacking propulsion, but the XKR-S is noticeably quicker again and freer revving at the top end. Partly this is because the S feels like it has a more aggressive throttle map – despite Jaguar's claims to have softened it across all XKs for the 2012 model year. Either way, this is a car where you find yourself backing out of the throttle halfway down a straight in an effort to keep speeds broadly moral.