A very rare prototype version of the Porsche 911 GT1 Streisen has been spotted on the road.

Regular readers of this site will be familiar with the mid-1990s Porsche 911 GT1 endurance race car and the public road-going homologation special known as the Straßenversion, German for "street version."

Only 20 homologation specials were sold directly to the public, all of which were built in 1997 and featured the front-end styling of the 996-generation 911s available at the time. However, four more prototypes were built, one of which made an appearance at the 2021 Concorso d'Eleganza Villa d'Este in Italy earlier this month. Fortunately, Automotive Mike was there and brought this video to our attention.

This particular 911 GT1 Straßenversion is one of only two prototypes built in 1996. One of them was owned by Porsche and the other was sold to Bahraini car collector Khalid Abdul Rahim.

These early prototype 911 GT1 Straßenversions were based on the 1996 911 GT1 race car, with the same 3.2-liter twin-turbo flat six in the mid-engine position (as opposed to the normal 911 rear engine position) The prototype's maximum power output was 54.5 kW. While the prototype had a maximum output of 544 hp, the race car had closer to 600 hp, and the brake rotors were also changed from the race car's carbon ceramic rotors to steel. The suspension was also not as extreme as the race car, but as the video shows, driving on the street was still next to impossible.

The two early prototypes were mechanically similar to the 20 customer cars that appeared later, but with some differences, the main one being styling similar to the early 993 generation 911s. The customer cars were also based on the 911 GT1 Evo racing car built for the 1997 motorsports season, not the 1996 911 GT1 racing car on which the two prototypes were based.

In addition, one prototype was built in 1997 that matched the specifications and design of the customer car built that year, and in 1998, an updated version of the 911 GT1 race car developed for the 1998 motorsports season, the one-off 911 GT1 Straßenversion homologation special was built as an updated version of the 911 GT1 race car developed for the 1998 motorsports season. These two 911 GT1 Straßenversion cars were succeeded by Porsche.