In 1982, the Fédération Internationale du Sport Automobile (FISA) restructured the production car category to consist of three new groups. Group B was for GT cars with a minimum of two seats, redefined as sports grand touring cars in 1986. It combined and replaced Group 3 and Group 4, two grand touring groups already used in rallying, and the production-derived Group 5 silhouette cars used in circuit racing.
The number of cars required for homologation—200—was just 4% of the other groups' requirements and half of what was previously accepted in Group 4. Homologation periods could be extended by producing only 10% of the initial requirement each subsequent year, resulting in Group B ‘homologation specials’—extremely rare cars produced solely to satisfy the homologation quota. Group B could be used to homologate production sports cars ineligible for Group N or A due to seating or production numbers, such as the Ferrari 308 or the Porsche 911. The low production requirement encouraged manufacturers to use competition-oriented space frames instead of unibodies.
Group B regulations allowed for significant modifications, with restrictions on forced induction engines applying an equivalence factor of 1.4 to engine capacity. For Wankel rotary engines, capacity was considered “twice the volume determined between the maximum and minimum capacity of the combustion chamber.” The equivalent capacity for turbine engines was calculated using a complex formula involving compressor pressure ratio and nozzle area. Ultimately, there were few restrictions on technology, design or materials.
The 1982 season saw the first Group B cars entered, but none reached the podium. In 1983, Hannu Mikkola won the driver's title in an Audi Quattro, though Lancia captured the manufacturers' title with the Lancia 037. Opel and Toyota also entered Group B cars, though with less success at the World Championship level.
In 1984, Audi beat Lancia for both titles, with Stig Blomqvist winning the driver's championship. Peugeot joined the competition with its 205 T16, beginning a period of dominance. Despite a crash that seriously injured Ari Vatanen, Peugeot dominated the 1985 season, with Timo Salonen winning the driver's title. New Group B cars debuted in 1985 from Lancia (Delta S4), Ford (RS200), Citroën (BX 4TC), and Rover (Metro 6R4).
The 1986 season saw competition from Peugeot, Audi (Sport Quattro S1), Lancia (Delta S4), and Ford (RS200). At the Rally de Portugal, Joaquim Santos crashed his RS200, injuring 31 spectators and killing three. The top teams withdrew from the rally, and Group B was placed in jeopardy. Disaster struck again at the Tour de Corse when Lancia’s Henri Toivonen and co-driver Sergio Cresto died in a crash. With no witnesses, the cause of the crash remained undetermined. Following this tragedy, and the earlier accident in Portugal, the FIA banned Group B cars from the WRC in 1987.
Although Group B rally car development ended in 1987, the cars continued to compete in regional championships, provided they met the limit of 1600cc for four-wheel drive or were homologated prior to 1984. Porsche’s 959 won the Paris-Dakar Rally in 1986, and Peugeot adapted their T16 for the same event, with Ari Vatanen winning in 1987, 1989, and 1990. Audi used their Group B experience to develop a production-based racing car for the Trans-Am and IMSA GTO series. Many ex-rally cars found homes in European rallycross events from the beginning of 1987 until the end of 1992.
The era of Group B is often considered one of the most competitive and compelling periods in rallying. The combination of lightweight chassis, sophisticated aerodynamics, and massive horsepower resulted in cars whose performance has not yet been surpassed within their category. Some rally enthusiasts refer to the Group B era as the “Killer B’s”, while others call it the golden era of rallying. Video games such as Gran Turismo Sport, Gran Turismo 7, and Art of Rally feature Group B cars, demonstrating their enduring appeal.
Source: Wikipedia article "Group B". No primary archives, autobiographies, period programmes, or specialist publications were consulted.