Jaguar XJ Speed and Sport upgrade top speed to 174mph

There aren't many ways to improve a Jaguar XJ. It's beautiful, fabulous to drive and -- in the case of the Supersport version -- even has a purple velvet glove box. What more do you want?

Oh, you wish it was faster, more aggressive-looking and had a better interior? Well you just so happen to be in luck, thanks to Jaguar's new Sport and Speed upgrade packs.

The optional Speed pack raises the electronically limited 155mph top speed of supercharged XJ models to a bum-loosening 174mph, meaning it'll blitz its BMW 7 series and Mercedes-Benz S class rivals in a drag race.

The Sport pack, meanwhile, lets you sprinkle various aesthetic tweaks to help the car stand out from the crowd. The exterior Sport pack brings aerodynamically optimised styling mods including subtle diffusers at the front and rear plus a bootlid spoiler. It also gets new-fangled 20-inch alloy wheels and red painted brake callipers with 'Jaguar' written on them. Swanky.

The interior sport pack, meanwhile, provides optional sports seats for both front and rear passengers and greater freedom to customise the cabin materials and colours, so now you can get that polka-dot hamster-skin roof you always dreamed of. Maybe.

The Speed pack is available on supercharged XJ models that have been fitted with the exterior Sport pack. Both the interior and exterior sport packs are available on pretty much every other edition of the XJ.

While you're lusting after the thing, make sure you read and watch our reviews of the 3-litre diesel Jaguar XJ and its ludicrously fast cousin, the XJ Supersport.