The McLaren F1 is a rare car, with just 106 copies made between 1992 and 1998. But the McLaren F1 GTR Longtail—the ultimate racing version of the F1—is rarer still. Just 10 Longtails exist and this one, currently offered for sale by U.K. exotic car dealer Tom Hartley Jnr. (and spotted by Road & Track) is the first one built.

The Longtail gets its name from lengthened rear bodywork, which, combined with a bigger rear wing and other tweaks, gave the car better aerodynamic properties than the standard F1 GTR. While the standard GTR had won the 24 Hours of Le Mans in 1995 (a feat the Longtail never matched), McLaren needed to upgrade the car to keep pace with rivals like the Porsche 911 GT1 and Mercedes-Benz CLK-GTR.

McLaren unleashed the Longtail during the 1997 racing season, but changes in the rules of major series soon made it obsolete. However, the Longtail name lives on in McLaren's "LT" series, which are more hardcore versions of brand's current road cars.

McLaren F1 GTR Longtail for sale (Photo by Tom Hartley Jnr.)

McLaren F1 GTR Longtail for sale (Photo by Tom Hartley Jnr.)

This car is chassis 19R and it was the first of two development cars built by McLaren in 1996 (the other is owned by former Pink Floyd drummer and noted car collector Nick Mason). It made its racing debut at the Suzuka 1000 KM and, according to the listing, has an extensive Japanese racing history. It was also the first Longtail to be made road legal by Lanzante and Gordon Murray Design. The car has made several appearances at historic racing events at places like the Spa-Francorchamps circuit in recent years.

The purchase includes a spares package, with all of the parts needed to convert the McLaren back to full race specification, if desired.

The dealer does not list a price, but expect to pay many millions of dollars to put this rare racer in your garage.