With only 350 cars built, the Jaguar XJ220 is a collector's item, but some examples are rarer than others.

Having relied heavily on Tom Walkinshaw Racing for the development of the XJ220 in the first place, Jaguar turned to the outfit when it came time to assess the possibility of a competition version. Three XJ220C race cars were born as a result, but in order to homologate them for competition, Jaguar and TWR built six roadgoing examples dubbed XJ220S. One of them is now going up for auction.

To create the XJ220S, TWR removed all the aluminum bodywork (except the doors) and replaced it with carbon fiber, adding a front splitter, rear wing and wider side sills in the process. That helped drive weight down to just over 1,000 kg (2,200 lbs), while the twin-turbo V6 was retuned to deliver 680 horsepower.

This particular car's owner recently had TWR install a titanium exhaust and recalibrate the engine output to nice round 700 hp. He also had it repainted the same shade of grey as the Lamborghini Reventon, fitted more modern headlights, and refurbished the magnesium wheels. As a result, RM Auctions expects it to fetch between $225,000 and $300,000 when it crosses the block in Arizona next month. Full details in the auction listing after the jump.

To create the XJ220S, TWR removed all the aluminum bodywork (except the doors) and replaced it with carbon fiber, adding a front splitter, rear wing and wider side sills in the process. That helped drive weight down to just over 1,000 kg (2,200 lbs), while the twin-turbo V6 was retuned to deliver 680 horsepower