The new Jaguar XFR-S is not simply a pumped-up XF. An uprated 543bhp version of the familiar 5.0-litre supercharged V8 is at the heart of the rear-wheel-drive XFR-S, and it also has a newly tweaked eight-speed auto gearbox that incorporates the Quickshift technology from the F-type.
Revised spring and adaptive damper settings result in suspension that is 100% stiffer than a standard XF saloon's. When combined with revised front suspension knuckles and new rear subframe, it contributes to a 30% increase in lateral stiffness.
The steering and electronic driver aids have also been recalibrated, and the aerodynamics have been altered to increase downforce, as illustrated by the more dramatic styling add-ons.
What’s the 2013 Jaguar XFR-S like to drive?
The XFR-S is as different from the regular XF line-up as you'd imagine, and we'd include in that the 503bhp XFR, which uses the same supercharged V8.
Everything about the Jaguar XFR-S feels wound tight. The steering is scalpel sharp, particularly in Dynamic mode. Even so, it still has the precisely weighted, silky-feeling steering that all XFs benefit from, and with familiarity you get used to the aggressive initial response.
Meanwhile, the V8 engine has become even more explosive. Power delivery is still progressive, but a more immediate throttle response and a better spread of torque lets the supercharged V8 pull even harder through a broader expanse of the rev range.
The gearbox does allow for smooth, well-blurred shifts in Drive mode, but stick it in Sport and it delivers staccato shifts late in the rev range, while the paddles give a rapid enough response to satisfy, even during hard track driving.
The throttle is easy to modulate, which is crucial because if you punch the pedal too hard too early, you could find yourself exiting the next corner with the nose pointing any way but forwards.
Ultimately, although the driver aids are effective, and the wide Pirelli tyres and keyed-in sense of communication are more than good enough to allow for hearty driving without scary moments, this is still one of the lairiest saloons out there.
It's not hard to drive quickly and fluidly on public roads, but hit Dynamic mode and try to glimpse the car's limits and you'll get out feeling like you've narrowly escaped a mauling. Depending on your view, this is either a reason to rush out and buy it immediately, or cause to look elsewhere for something less dependent upon bravery.
At least the enormous brakes deliver brutal stopping power, and great feel through the pedal for smooth use in normal driving, and ride quality hasn't suffered as much as you might imagine. Body movement is kept ruthlessly in check and the car feels rigid and firm, especially when you're really pressing on.
The downside to all this is that some of the suppleness of lesser XFs is missing. So rather than serving up a lovely creamy ride it thunks over potholes and speedbumps. You may of course feel that this is a price worth paying for its prodigious abilities elsewhere but if you're used to the way other Jaguar saloons soak up road scars it's quite a shock.
Refinement elsewhere is hit and miss, with those huge tyres kicking up lots of noise over certain surfaces, although most of the time you'll be preoccupied with the raucous exhaust note anyway.
What's the 2013 Jaguar XFR-S like inside?
The pleasant standard XF interior is still in evidence, including the rising rotary gear shifter, cool blue mood lighting and 7.0-inch colour touch-screen.
The leather sports seats are the same as those found in the XFR, although some owners might want even grippier, full-on bucket seats. Still, in general road use the existing ones do a good job of being comfortable and supportive enough in fast cornering.
Rear passenger space is a way off class best, particularly for headroom, although you'll still be able to sit two average-sized adults in comfort.
You won't need to add any extras. The XFR-S gets the carbonfibre rear spoiler and full bodykit, as well as the electrically adjustable leather seats, sat-nav, DAB radio, Bluetooth, full iPod connectivity and 12-speaker sound system, rear parking sensors, climate and cruise control.
Should I buy one?
The only reason you ever would is because you valued the sheer voracity of the £80k XFR-S. That's understandable; it's a riotous thing to drive.
However, it is also up against cheaper and more rounded rivals. The Mercedes-Benz E63 AMG and BMW M5 cost less yet are actually faster to 62mph. In particular, the Mercedes does come close to the Jaguar's drama, but offers more forgiving daily useability.
Perhaps an even harder rival for the XFR-S to compete with is the standard Jaguar XFR, which is cheaper by over £14k, undercuts the Merc and BMW, and still offers a really intoxicating blend of light-footed but dramatic handling, not to mention a softer ride.
The XFR-S is dazzling, but much of the competition is easier to justify.
What Car? says...
Mercedes E63 AMG
Engine size 5.0-litre V8 supercharged
Price from £79,995
Torque 502lb ft
0-60mph 4.4 seconds
Top speed 186mph
Fuel economy 24.4mpg