The German firm Mechatronik may specialize in restoring and selling classic Mercedes-Benz cars, but the shop currently has a very special Porsche 959 listed for sale. It's no normal 959; it's a prototype of Porsche's first supercar.

First spotted by Motor1, this car is the seventh of 12 F-Series prototypes, which were built just before pre-production and pilot production vehicles. Finished in Ruby Red, it was used for hot weather testing and electrical-systems testing in the U.S. and Europe. That level of testing was unusual for an exotic car at the time, but Porsche wanted to make sure the 959 was usable everywhere. To prove the 959's mettle, Porsche also entered it in the Paris-Dakar Rally.

During testing, the car was fitted with multiple interior layouts, including one with different seats, according to the listing. It still has extra wiring under the passenger seat, and mounting points for testing equipment.

Porsche 959 prototype (photo via Mechatronik)

Porsche 959 prototype (photo via Mechatronik)

This prototype is also missing a few items from 959 production cars. It lacks power steering, a fuel filler cap, ride height control, rear seatbacks, a passenger-side exterior mirror, an alarm, and a windshield washer.

Porsche destroyed most of the F-Series prototypes (Mechatronik estimates only three or four survive), but this car was imported to the U.S. and displayed at the headquarters of prominent Porsche dealer Vasek Polak. It was then sent to Japan for demonstrations, and subsequently went to Belgium, and then the United Kingdom. Its odometer currently shows 16,478 miles.

Mechatronik doesn't list a price, but this car was put up for auction in 2018 with an estimated value of $1.3 million to $1.6 million. Even a wrecked 959 production car fetched $467,500 at auction that same year.