Group B was a category of racing cars, introduced in 1982 by the FIA (Fédération Internationale de l’Automobile), whose technical regulation was established to regulate circuit and rally competitions. Group B was introduced as a replacement for both Group 4 and Group 5 cars. The new regulation fostered some most powerful and sophisticated rally cars ever built. The cars of those years reached powers of 600 hp which moved masses of about 900 kg. The performances were impressive, accelerations 0-100Km/h reached in 2.5/2.7 seconds. Even the maximum speed, in the special stages, was over 200Km/h. Group B was initially a successful formula, many manufacturers joined the world rally championship and crowds of increasingly large spectators followed the races. The low homologation requirements quickly attracted manufacturers to Group B. Lancia 037, Peugeot 205 T16, Ford RS200, Metro 6R4 are some of the jewels of those years, But the most powerful cars of that period were the Audi Quattro S1 and the Lancia Delta S4 Audi made 224 Sport Quattro road-specs and parallel developed various increasingly evolved racing versions. the Sport Quattro S1, the Sport Quattro S1 E2 and the Sport Quattro S1 E2 Pikes Peak. In 1987 the Sport Quattro S1 E2 was aesthetically characterised by striking aerodynamic appendages such as the large front spoiler and large rear wing. The engine was upgraded to produce 600hp and was equipped with a system that avoided turbo-lag. The Audi team used it only in 6 world rally races before retiring from the rallies. Audi Sport Quattro S1 won Pikes Peak in 1985 with Michèle Mouton and the following year with Bobby Unser. Walter Röhrl at the debut on the Pikes Peak Hillclimb with a specially prepared Sport Quattro S1 E2, won the 1987 edition, breaking the 11-minute barrier with the new record time of 10’47 “85. Lancia replaced their outclassed 037 with the Delta S4 which featured both a turbocharger and a supercharger for optimum power output. The engine of this car was a 4-cylinder in-line with a displacement of 1759 cm³ The advantage of the Volumex compressor was to push already at 1,500 rpm, while the “pure” power came instead from the KKK exhaust gas turbocharger. The Delta S4 road-specs had 250hp, the race version at its debut in 1985 had 480hp, while the latest 1986 evolution develops 650 HP (476 kW) with a supercharging pressure of 2.5 bar via an over-boost.