Today, all forms of international motor sport involving land vehicles with four or more wheels come under the jurisdiction of the FIA.
For many years, the FIA delegated the organisation of motor sport to an autonomous committee, the CSI (Commission Sportive Internationale or International Sporting Commission) which eventually became FISA (or Fédération Internationale du Sport Automobile) in 1978 and was fully integrated into the structure of the FIA 15 years later. In the early 1970s, prevailing CSI regulations allowed production vehicles to compete in four classes or groups i.e Group 1 through to Group 4. Similarly, single seaters were classified as Formula 1, 2 or 3.
Group 2 cars were commonly known as 'Touring Cars', with Group 3 as 'Production Grand Touring Cars' (minimum 1000 units produced over two years) and Group 4 as 'Limited Production Grand Touring Cars' (minimum 400 units).
Group 5 and 6 regulations were introduced in 1976. This came following pressure from German and British manufacturers who were concerned that international sports car racing had been weakened by the increasing lack of production-type vehicles on the grid. This was fine for Le Mans, went the argument, but there was little incentive for manufacturers to enter prototype cars for an entire season.
The idea behind Group 5 was for production cars that were eligible for Groups 1 to 4 but with major modifications carried out and thus it became known as the 'silhouette formula'. This refers to the fact that the cars would retain their visual identity in outline from the side - essential for promoting the brand - but with virtually any other bodywork or mechanical modifications permissable. The idea was intended to pull together saloon and GT manufacturers for one enormous international series - the FIA World Championship For Makes (WCM).
Among the manufacturers who had pushed for the change were Porsche, who had been preparing for a long time with the development of their 935 (Group 5) and 936 (Group 6) cars. In fact, Porsche triumphed heavily early on with these technologically advanced machines. This dominance drove the cost of building competitive cars higher and higher and forced the Group 5 formula to eventually fail. This led to the introduction of the Group C formula for prototype cars which flourished throughout the 1980s.
However, for four or five years in the late '70s and early '80s, Group 5 racing provided a spectacular sight for motor sport fans. From 1976, the WCM was run as a Group 5/6 series and a year later, ADAC permitted entry of Group 5 cars into its German national touring car series, the Deutsche Rennsport Meisterschaft (DRM). As time progressed, the DRM actually became better supported than the WCM and was more or less the dominant Group 5 series until the health of the formula declined in 1981. This happened as it became dominated by Ford and Porsche against whom nobody could afford to compete.
The most well known Group 5 cars were all spectacular - firstly the Ford Team Zakspeed Escorts (then the Capris of course), the Porsche 935 derivatives (the factory '77 & '78 cars plus Kremer and Joest versions), the BMW 320 and M1, the Toyota Celica LB and and the Lancia Montecarlo Turbo.