Quick quiz time- What's the fastest Jaguar ever, not counting the XJ220? Answer: you're looking at it. This new XKR-S has been de-restricted, so the standard XK-R's limited top speed of 155mph does not apply. Good.
This baby will run all the way to 174mph, which seems a lot more Jaguarish to me than a computerised restrictor. Here's a thought - remove the restrictors from all Jaguars. Just a thought.
Few owners will ever hit this car's maximum, but it's nice to know it's there. And the S is an improvement over the standard car in many other ways, all of which add up to a full and proper justification for the extra £9,000 on the list price.
Not least of the improvements is the superb body kit. This is instantly recognisable as the ultimate Jaguar XK, and a good many buyers will wear the extra cost for that reason alone. Lower front, side and rear skirts are subtle yet still striking, and work beautifully on the XK's fundamentally gorgeous shape - to such an extent that a couple of people asked me what the car was.
The rear diffuser combined with the larger rear wing really transforms this car's back end - the haunches look a lot more muscular and the bespoke wheels are absolutely perfect. Once again, this is a Jag that cocks a finger in the direction of Aston Martin, and I don't think there's an Aston to touch it, really.
Then there's the suspension upgrades. Jaguar's chassis gurus are surely the greatest in the business this side of Lotus. They've done some of their best work with the XKR-S, which is significantly harder all round for better response through corners, yet somehow maintains its cosseting ride.
If there's any GT car in the world with a better ride and handling compromise than this XKR-S, I haven't driven it.
The engine remains the same - a 4.2-litre supercharged V8 with 420bhp and 413lb ft - and so does the transmission, the six-speed auto by ZF - and I guess these are the only two areas that need updating. New, more efficient engines are on the way later this year, but there isn't a lot wrong with the drivetrain now. I'd like to see more controllability built into the auto 'box, though, like in the XF - it's an improvement Jaguar should make straightaway.
That's nit-picking, though. The way this car goes, stops and steers makes it the best Jaguar on sale, and probably the best GT too.
By Bill Thomas from Top Gear