Adding the new Speed Pack to the V8-powered, Supersport version of the XJ luxury saloon raises its electronically limited top speed from 155mph to 174mph.
There's no increase in power over the 'standard' car; you still get 502bhp. However, Jaguar has made changes to the engine management and tyre pressure monitoring systems to help them cope with the higher top speed.
The Speed Pack also brings red brake callipers, some aerodynamic modifications to the body and new 20-inch alloy wheels.
What's the 2012 XJ Supersport Speed Pack like to drive?
Not that different to the standard Supersport. The smooth supercharged V8 is sublime, offering instant acceleration at any speed. Its only really the higher top end that sets the Sport Pack car apart.
At any speed the XJ impresses. It simply glides over bumps and cracks on the road, while the combination of precise steering, strong grip and minimal body roll is astounding in a car that weighs the best part of 1900kg and is over five metres long.
Refinement is also top notch; you hear only good noises from the engine, and wind noise isnt an issue.
All this can be said of the XJ Supersport without the Speed Pack, however, and the benefits of such a high top speed simply aren't applicable on UK roads.
What's the 2012 XJ Supersport Speed Pack like inside?
The cabin is identical to the standard Supersports, so it features beautifully stitched leather, comfortable seats with loads of electronic adjustment and Jaguar's signature rising rotary gear selector.
It has a digital dashboard display and a touch-screen multimedia system, too.
There's plenty or room in the front, but headroom is a little tight in the rear.
If you prefer to be chauffeured, its worth considering the long-wheelbase version, which offers an extra 125mm of rear legroom for a 2745 premium.
Should I buy one?
If you regularly zoom up and down German autobahns or your driver does then you could utilise the higher top speed the Speed Pack brings.
It does add 3700 to the price of the standard wheelbase Supersport (3445 to the long wheelbase), but thats not a whole load of cash when the car costs around 91,000 to begin with.
The new Audi S8, however, is more than 10,000 cheaper, as well as more powerful, faster-accelerating and easier on fuel; it averages over 27mpg, compared with the XJ's 23.4mpg.
The A8 is the more sensible choice, then, but if you drive your limo yourself, youll probably have more fun in the Jaguar. Just be sure to ask yourself whether you really need the Speed Pack. For the vast majority of UK buyers, it's pointless.
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