The Porsche 959 was designed to comply with FIA Group B regulations. In theory, it could compete with other Group B rally cars like Audi Quattro Sport, Lancia Delta S4 and Peugeot 205 T16 in the World Rally Championship, which was the most exciting and most sophisticated rally category ever appeared.
But a whole season of WRC might cost dozens of million, which was not affordable by a car maker producing 50,000 cars annually.
So Porsche very cleverly chose the Paris-Dakar race for advertising purposes, and simultaneously to test the reliability of 959 in the worst conditions.. It was the most famous event in the world, commonly known as the worlds toughest rate. But competition was far less than WRC, and unlike the World Rally Championship which required 200 cars be built to be eligible for competition, the Dakar didn't require a minimum number of cars built for homologation.
The program began in 1984. The Porsche 953 was a variant of the 911, designed and built specifically to compete in the 1984 Paris–Dakar Rally. The 1984 cars were little more than 3.2-liter 911 4x4s raised up accordingly. It is sometimes referred to as the 911 4x4, as it used the developmental, manually controlled four-wheel drive system that was intended to be used on the 959. Traveling on an extremely enhanced suspension, powered by a 300 bhp (224 kW), 6-cylinder engine, and weighing in at 2,750 lb (1,247 kg), it was extremely successful.
The three 1985 cars that already looked like 959s were missing the twin-turbo engine, as well as the latest evolution of Porsche's four-wheel drive system. Porsche used the mule of a 959 with the powertrain of a 911 Carrera 4, only to retire all three cars with mechanical problems. With no Porsche finishing, the '85 Dakar went to a Mitsubishi Pajero Evolution.
For 1986, the Dakar Porsche's finally got all the upgrades from the 959 project, including the active four-wheel drive system offering four driving modes adjusted by the computers. This gave Porsche a 1-2 finish, with supporting 959 Dakar engineer Unger Kussmaul crossing the line at sixth. If the third car did not act as a service car (it packed the spare tires and repair kits for the other two), it could have finished 3rd !!
The 959's 2.85-liter engine features double overhead cams with four valves per cylinder, a seven-bearing crankshaft and six titanium connecting rods, air-cooled cylinders with a water-cooled head, and of course a pair of two-stage sequential turbochargers supplied by long-time Porsche partner Kühnle, Kopp & Kausch
With four traction modes available on-demand, the 1986 Dakar 959s were also detuned to 400 horsepower to be able to run on gasoline as low in quality as 86 octane available in the deserts across Algeria, Niger, Mali, Mauritania, Guinea and Senegal. Fifty-three-gallon tanks were filled up over and over again so that after 22 days and 8,700 miles off-road, Metge and Ickx could score Porsche's 1-2.
By the time the 959 was ready for production and homologation in 1987, the Group B program was canceled altogether a year prior thus ending Porsche's participation in Group B.
The twin-turbocharged 959 would go on to become the world's fastest street-legal production car when introduced, achieving a top speed of 317 km/h (197 mph), with some variants even capable of achieving 339 km/h (211 mph). During its production run, the 959 was considered as the most technologically advanced road-going sports car ever built, and forerunner of all forthcoming sports cars. It was one of the first high-performance sports cars with all-wheel drive, providing the basis for Porsche's first all-wheel drive 911 Carrera 4 model. Its performance convinced Porsche executives to make all-wheel drive standard on all turbocharged versions of the 911 starting with the 993. The twin-turbo system used on the 959 also made its way to future turbocharged Porsche sports cars.