Group B was a set of regulations introduced in 1982 for competition vehicles in sportscar racing and rallying regulated by the FIA. The Group B regulations fostered some of the quickest, most powerful and sophisticated rally cars ever built and is commonly referred to as the golden era of rallying. However, a series of major accidents, some of them fatal, were blamed on their outright speed and lack of crowd control. After the death of Henri Toivonen and his co-driver Sergio Cresto in the 1986 Tour de Corse, the FIA disestablished the class, which was replaced as the top-line formula by Group A. The short-lived Group B era has acquired legendary status among rally fans.
Group B was introduced by the FIA in 1982 as replacement for both Group 4 (modified grand touring) and Group 5 (touring prototypes) cars.
Group A referred to production-derived vehicles limited in terms of power, weight, allowed technology and overall cost. The base model had to be mass-produced (5000 units/year) and had to have 4 seats. Group A was aimed at ensuring a large number of privately owned entries in races.
By contrast, Group B had few restrictions on technology, design and the number of cars required for homologation to compete—200, less than other series. Weight was kept as low as possible, high-tech materials were permitted, and there were no restrictions on boost, resulting in the power output of the winning cars increasing from 250 hp in 1981,the year before Group B rules were introduced, to there being at least two cars producing in excess of 500 by 1986, the final year of Group B. In just 5 years, the power output of rally cars had more than doubled.
The category was aimed at car manufacturers by promising outright competition victories and the subsequent publicity opportunities without the need for an existing production model. There was also a Group C, which had a similarly lax approach to chassis and engine development, but with strict rules on overall weight and maximum fuel load.
Group B was initially a very successful group, with many manufacturers joining the premier World Rally Championship, and increased spectator numbers. But the cost of competing quickly rose and the performance of the cars proved too much resulting in a series of fatal crashes. As a consequence Group B was canceled at the end of 1986 and Group A regulations became the standard for all cars until the advent of World Rally Cars in 1997.