Jaguar XKR-S

What is it?

The quickest ever version of the XK – and the fastest Jag since the XJ220 supercar. Most of the extra pace comes from a special ‘driver focused’ chassis, developed by XK chief engineer Russ Varney and driving guru Mike Cross.

In the manner of many of the best performance cars, the XKR-S is a ‘skunk works’ project conducted by senior engineers around other projects – and which Jaguar’s management green-lit when they discovered it was so good.

The good news is that there will probably be versions of other Jaguar models similarly aimed at the keenest drivers. The ‘S’ sticks with the regular XKR’s 4.2-litre, 420bhp supercharged V8, mainly because the investment needed to raise the power would be prohibitive (and there’s a 5.0-litre V8 coming soon). However, ditching the electronic speed limiter lifts top speed to 174 mph.

What’s it like?

In a word, brilliant. A bald description of the mechanical changes doesn’t really do justice to the job; it’s the subtlety and judgement exercised on the way to the improvements that make the car so good.

The standard XKR is already a superb driving appliance, and the S gains firmer springs, dampers and anti-roll bars, steering is 10 per cent quicker and the ride height has been lowered by 10mm. It also gets race-bred brake calipers that not only improve stopping power but also reduce unsprung mass.