An epic supercar battle raged in the late 1980s between the Ferrari F40 and Porsche 959. With analogue rawness, the F40 competed against the computerised 959 on the road, track, and in games like The Duel: Test Drive II. The Ferrari was considered more performance-oriented than the Porsche. However, that equation changed with the 959 Sport. 

Recently Henry Catchpole had an opportunity to drive a Porsche 959 Sport for an episode of The Driver's Seat. Known as F9, it's one of the first prototypes of the 959 and arguably one of the fastest 959s ever built. Most 959 Sports are about 100 kilograms, or about 220 pounds lighter than the 959 Comforts, but F9 is speculated to be 200 kg lighter, the equivalent of 440 pounds.  

In addition to the lighter curb weight, the 959 Sport received a more powerful version of the twin-turbo flat-six, which saw output increase from 450 bhp to 508 bhp. Equipped with all-wheel drive, performance was astonishing even for today, including a 0 to 60 mph time of 3.6 seconds and a run to 100 mph in just 8.3 seconds.  

As a prototype, F9 is a bit rough around the edges. It was used to test transmissions in climates as diverse as Sweden and Algeria. It lacks the standard tailpipes of the 959, making do with ordinary turned-down ones that look like the dual exhaust on a classic muscle car. And there are about a dozen other minor differences, including a differently shaped wing, lack of headlight washers, and some obviously handmade parts. 

Taken as a whole, the rough edges add character. Yet it's a complete car that's easy to take for granted when driving because of how well it performs. But what makes it astonishing is that the 959 competed in a diverse array of events, including the Paris Dakar Rally and the 24 Hours of Le Mans.     

F9 was recently listed for sale with Girardo & Co at an undisclosed price. Normal Porsche 959s rarely come up for sale, and when they do they fetch between £1.5 and 2.0 million pounds. Special versions like surviving prototypes command a lot more money. And as the car considered the fastest 959 to leave the factory, F9 is very special indeed.