Road Test: Jaguar XK 5.0 Supercharged V8 R-S 2dr Auto

The noise comes as a surprise. The standard Jaguar XKR is a smooth character - not hushed, exactly, but always refined. The new XKR-S is a coughing, cackling, fuel-snorting loon, emitting a metal-edged bellow at any opportunity and mooching around with all the subtlety of a trigger-happy chainsaw operator in a public library.

It's a mighty clear indication what the XKR-S - essentially a turn-all-the-knobs-up-to-11 iteration of the XKR - is about. Despite packing 542bhp and a top speed of 184mph it isn't, as the marketing types claim, the fastest and most powerful Jaguar ever: 1991's XJ220 boasted the same power output and could manage 217mph flat out.

See more pics of the Jaguar XKR-S

But it's a razor-edged thing nonetheless. Thanks to an engine remap and exhaust tweak, power is up by 32bhp over the XKR. The fixed carbon rear wing and vertical vents either side of the Jag's gaping mouth don't do much for the coupe's svelte lines, but they help reduce high speed lift by 26 per cent. Tougher front suspension, 26 per cent sharper springs and lightweight 20-inch alloys all add up to a 4.2-second 0-62mph time and a sub-eight minute Nordschliefe lap.

You might worry that this puts the XKR-S in a tricky place. The XKR has always steered clear of the track-focused fistfight, instead carving out a niche as a super-fast grand tourer. Might the bulked-up Jag have forgotten its USP?

Not to worry. The XKR-S retains Jaguar's trademark delicacy of ride: firm but never harsh, planted but pliable. Yes, it's noticeably stiffer than the XKR, but never brittle. No company in the world does damping better than Jaguar... and no company makes a better supercharged engine. As the 5.0-litre V8 winds up past 4500rpm, the speed piles on so quickly that things start to get a bit blurry, the supercharger's scream accompanying a worrying tendency of the distant horizon to attack the windscreen at pace.

This much we expected. But the XKR's most impressive trick is how much more wieldy it feels on tight, twisty roads than the XKR, tucking into corners far more deftly and generally feeling more compact than its generous dimensions suggest. Grip levels are mighty, the wider rear tyres clinging onto even cold, damp tarmac with improbable tenacity. The only issue is over the steering: slowed slightly to reduce twitchiness at the extreme speeds of the XKR-S, it's a touch short on feel.

Actually, there is one more issue, and one that reads something like this: £97,000. That's a serious price tag, £20,000 north of the standard XKR, and in the domain of some serious metal: the Audi R8 V10, a kitted-up Porsche 911 GT3 and, most significantly, the new Aston Martin Vantage S.

But the XKR-S is more than good enough to earn its place in such stellar company. Brilliant on the autobahn, just as good on a mountain pass, this is one of the truly great GTs. That noise is just an added bonus.