Arguably one of the greatest Porsche road cars ever built, the 959 was an instant icon due to its supercar performance and exclusivity. Just 337 units were built, running to 60 in under four seconds. When it debuted in 1986, it had the prestigious title of being the world's fastest street-legal production car with a top speed of 195 mph. Built originally for Group B homologation, the 959 was the sportscar-maker's first high-performance model to have all-wheel-drive, paving the way for today's 911 Carrera 4.

What's more, the 959 is what convinced Porsche execs to included AWD in all future 911 Turbos beginning with the 993. But before the 959 reached production, test mules were used for development, and now one of the two running prototypes is heading for the auction block at the Barrett-Jackson event in Scottsdale, Arizona, later this month. The car you're looking at still has its original pre-production Dunlop tires as well as its original prototype light-weight alloys. Originally there were 29 prototypes, all of which were used for final testing, media events and other road tests as Porsche readied the concept for production - much as it is with the 918.

However, most of them were destroyed once the 959 project ended. What's more is that Porsche no longer releases prototypes to the public, making this pre-production 959 all the more special. Power comes from a 2.85-liter twin-turbocharged six-cylinder boxer engine mated to a six-speed manual. With 444 horsepower on tap, the 959 could go from 0-62 mph in only 3.7 seconds. Unfortunately, whoever buys this prototype won't be able to verify those performance numbers. Because it is still considered a prototype, the car is not certified to drive on public roads. Despite that, we have no doubt someone will be more than willing to pay top dollar for it.