Jaguar is working on a more powerful version of the sporty XF sedan: the XF-R that set to be launched in 2009. It will compete with models like BMW M5, Audi RS6 and Mercedes E63 AMG.

The latest spy shots caught a prototype that runs a 4997cc V8 – the new-generation engine that will be rolled out across Jag/Land Rover, with direct injection and the latest tech to trim the naughty numbers (g/km and mpg) and boost those desirable digits (bhp and lb ft).

The XF-R will be a supercharged model, so the output will be around 500bhp.

The XF-R has a noticeably different snout, as witnessed by the larger air intakes and bonnet scoops, but the rest of the front of the car is admirably restrained. The side profile is differentiated by stout side sills.

If you're looking at the rear of the XF-R (and let's face it, most of us will be), you'll be following a subtle lip spoiler on the bootlid, chunky quad pipes and probably a discrete diffuser.

.