Until recently, Jaguars virtually came with the faint smell of old man, stale cologne and boiled sweets. Jaguar lovers will drone on about Le Mans in the 1950s and that the Mk2 was the bank robbers' getaway car of choice in the 1960s, but in case anybody hadn't noticed, that was long, long ago.

But under the new Indian ownership, there's a renaissance: the Leaping Cat is finally showing its claws after decades limping through the automotive wilderness. The XF is the car that can take the fight to BMW and Mercedes, and with a little German input could blow them clean off the map.

Because with a major rework Arden didn't even need the 5-liter XFR; they have turned the lesser SV8 into the 550-hp Arden AJ21. And as the needle raced past the 130-mph mark and the induction whine screamed over the bass-heavy Spitfire of a V8 engine that gains new life with the new sports exhaust, this Jaguar suddenly seemed the youngest, hippest cat in the field.

The base 4.2-liter is more or less Spitfire vintage. It is so far beyond its sell-by date it's grown mold and started to smell. But with a little bore and stroke increase and a larger twin-screw supercharger, Arden has created a 4.5-liter masterpiece. Of course it's more complex than that and the new crankshaft, pistons, con-rods and cooling systems mean this surgery can only happen in-house at the company base in Krefeld. For those who can't make the trip, Arden will ship a larger supercharger, good for 470 hp, which can be fitted at your friendly local Jag dealer worldwide. In truth that should be enough, but, well, you can never really have too much power.

Because this car will blast through the 60-mph mark in 4.8 seconds and without the interference of a top-speed limiter will go through the 183-mph mark with ease. That's way down from Jag's own XFR, which topped 225 mph on the salt flats, but then again that test car was hardly standard. And if it's a taste of things to come when Arden gets to work on that new machine, we'll take it as a good sign.

As it is, this AJ21 comes laden with three things BMW forgot to include in its own technical M5 masterpiece: character, torque and style. That starts with Jaguar's own factory work, with the interior bathed in blue light and the gear selector that rises from the floor like a megastar in concert. With a push of the pulsing starter button, the V8 comes to life with a chugging, menacing vibration that somehow embodies the big cat. Each blip of the throttle brings a gunfire crack. Even though, like most modern cars, it won't let you stand on the brake, gas it and slide off into the distance, it's still mighty impressive on a standing start and all the way through the rev range thanks to gloopy dollops of torque.

The peak torque figure of 472 lb-ft represents almost 30 percent more than the M5 can muster, and that's something you can feel at every opportunity for overtaking. This is the faster car in the real world, as you don't have to think about flipping the paddles for a downchange; just bury the throttle in the thick carpet and the car takes off like, well, a scalded cat.

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