One of the rarest Ferrari F40s is changing hands.

The only example of the legendary supercar powered by a V-12 will be auctioned by Iconic Auctioneers at this year’s Silverstone Festival later this month. The competition-class speedster was built by UK-based Simpson Motorsport to the Italian marque’s approval.

The F40 may have been the first Prancing Horse to break the 200-mph barrier—it briefly became the world’s fastest production car—but it wasn’t powered by one of the company’s famous V-12s. Instead, its engine bay was filled with a twin-turbo 2.9-liter V-8 producing 471 horsepower. That wasn’t enough for race car driver Stefano Sebastiani.

Heading for the auction block, the F40 began life as a test mule. Following crash tests, the chassis was offered to Sebastiani by the Maranello-based automaker with whom he had a working relationship. He then commissioned Simpson Motorsport to rebuild the car, but instead of restoring it to factory spec, he wanted it to be fitted with the naturally aspirated 5.5-liter V-12 from the 550 Maranello. Needless to say, it was an expensive process, but it did boost the car’s output to 542 horsepower, Drive reported.

Other changes included the use of the Hewland transmission (upgraded to a six-speed sequential transmission in 2005), a lightened F40 GTE race car body, and the fitment of an FIA-spec roll cage. Despite the addition of the latter feature and the use of a heavier mill, the car is said to tip the scales at just 2,370 pounds. The standard road-going F40 weighs 2,765 pounds (and 3,018 pounds in the US) with compression.

This V-12 F40 was designed and built for the race track. Indeed, the car competed in a number of events between 2002 and 2006. During this time it participated in 13 races, finishing second at the Britcar Oulton Park circuit in spring 2006. When its race days were over it was put into dry storage and has been regularly maintained since then.

The 1992 Simpson-Ferrari V-12 GTR will be up for auction on the first day of Iconic’s Silverstone auction, which runs from Friday, August 23 to Sunday, August 25. The auction house expects the unique race car to fetch between £500,000 and £600,000, or around $639,000 to $766,000.

Click here for more photos of the 1992 Simpson-Ferrari V-12 GTR.