Part 3: 1970-1975 The Ford and BMW years

1970 saw the introduction of new rules, which could be characterized as a mixture of old group 2 and group 5 rules. Still, 1000 cars had to be produced, but these could be modified quite freely. Supercharging was not allowed except when this was a standard option. No supercharged car was ever raced, although Schnitzer came very close when building (but not racing) a BMW 2002 turbo. At the start, the championship was divided into 3 divisions: 0-1000 cc, 1001-1600 cc and over 1600 cc. In 1971, things were changed, and the divisions were now 0-1300 cc, 1301-2000 cc and over 2000 cc. In 1972, a maximum engine size of 5000 cc was introduced, which ruled out any Mercedes 300 SEL 6.3. Later, this ban was lifted. Finally the smallest division was dropped in 1973, under heavy pressure of BMW and Ford, to end Alfa Romeo's chances with walking away with the championship, while a war raged between Ford and BMW..

Porsche tried to homologate the 911 as a touring car, but they went too far, trying to get basically the same car in group 2, 3 and 4. Rear seating room was decided to be too small by FIA, so the car was out. On the other hand, Alfa Romeo got it right and could race the 1300 GTAJ and 2000 GTAm - and old faithfull GTA 1600 became a GT and raced in group 4...

Ford choose to enter a massive works team, which failed in 1970 but took a stranglehold on overall results from 1971 until mid-1973. A decision by FIA then almost killed the championship; from 1973, only 100 cilinder heads (with 4 valves and DOHC) had to be built in order to be used in racing. The same counted for spoilers. Clever homologation brought BMW in front, and they never looked back. After the fuel crisis of 1973, the works entries became sparse, so the championship was left to privateers with very expensive cars.