The Jaguar XFR is the British company’s rival to the BMW M5 and the Mercedes E63 AMG.

The XFR builds on the now familiar XF saloon recipe but is powered by a 503bhp direct injection supercharged V8. It also gets substantial chassis changes, including different spring rates, a newly developed continuously variable electronic damping system and a new electronically controlled rear differential.

Deputy editor
The XFR's talents aren't surprising when the base model is so good

The new XFR also benefits from enhancements to the steering over the standard car.

The visual changes are subtle but effective. There’s a redesigned, XJ-esque front end with a more aggressive look and added air intakes. It also gets flared sills, a discreet boot lid spoiler and standard 20-inch alloy wheels.

Inside there are further additions such as special dials, dark wood and more heavily bolstered, but extremely comfortable, seats.

The supercharged V8 in the Jaguar XFR is an absolutely magnificent engine. It makes the car almost indecently quick.

And it’s this engine, allied to the familiar but fettled 6-speed ZF auto ‘box - now operated by a rotary dial - which gives the Jaguar XFR such headway over its rivals. The torque and the effectiveness of this gearbox make it brilliant docile when you want to make chilled progress, but also crushingly effective when you want to flex your right foot and get moving.

Maximum torque of 461lb ft is dished out from 2500rpm to 5500rpm. So once you get it percolating, performance is astonishingly relentless. The 0-60mph dash is despatched in 4.7sec, but really telling is that 50-70mph is demolished in just 1.9sec, making it a demonic overtaking tool.

All that torque means that it gets into its stride at little over tickover and when it does performance is intoxicating, as is the V8’s delicious repertoire of noises: which don’t, for the first time on a supercharged Jag, include a whine unless you’re on full throttle.

The Jaguar XFR’s substantial chassis changes are instantly noticeable. For a start there’s an additional firmness to it and far more bumps are telegraphed through to the cabin. This isn’t just noticeable at urban speeds but even at three-figure pace. However, the fact that it’s all so quiet and controlled still makes the Jag a very credible cruising tool.

Yet the loss of some suppleness is more than made up for by the way the XFR simply gobbles up challenging roads. A quicker steering rack, plus the other chassis changes make it far more agile than 'cooking' models.

It turns in brilliantly, has almost endless grip and the electronics allow you to get on the gas really early in a corner – easily making it the equal of the BMW M5 through both fast and slow corners.

The XFR's composure is first class. The new electronic damping system does a great job of keeping the body taut and flat even when you’re doing the sort of speeds on the sort of undulating roads that require the maximum amount of wheel travel.

The rest of the experience is regular Jaguar XF plus an extra ten per cent. Yes, there’s a little more road noise and Jaguar still hasn’t managed to eradicate wind fluttering around the wing mirrors. But one of the great car cabins has been made even better in the R version.

The new sports seats are much improved over the standard items, and there are additional trim flourishes that let you know that you’re in the sports models but it doesn’t even get close to tackiness or displaying a lack of taste.

If you want the best all-round high-performance saloon the Jaguar XFR is the answer. It’s the equal of the BMW M5 dynamically and for sheer performance; yet is far easier to live with day-to-day and far more compliant when you’re not in the mood for maximum attack.

While the rivals from Merc and Audi have hot-rod grunt and plenty of other appealing characteristics, but they both lack finesse and both need a lower price tag.