Group 4 (motorsport)

Lore & Background

Group 4 was first applied to sports cars complying with FIA Appendix C regulations, as well as touring and GT cars modified beyond their original homologation groups. In October 1964, the FIA announced an overhaul effective from 1966, requiring a minimum production of 50 units in 12 consecutive months and road-legal equipment. This led to the homologation of the Shelby 427 Cobra Mk3, Ford GT40 Mk1, and Ferrari 250 LM in early 1966, though the Cobra and Ferrari were controversial. After Ford's 1967 Le Mans win, the FIA imposed a 5000cc engine limit for 1968 and allowed the Lola T70 to be homologated by counting earlier open-top cars toward the total.

In April 1968, facing small Group 6 prototype fields, the FIA reduced the Group 4 minimum production to 25 units for 1969. Porsche built 25 Porsche 917s for homologation in April 1969, and Ferrari produced the Ferrari 512S in January 1970. These cars were essentially Group 6 prototypes with 5-liter engines instead of 3 liters, allowing them to compete for outright wins. For 1970, the limited-production sports car category was renamed Group 5, and Group 4 became the class for special grand touring cars with a minimum production of 500 in 12 consecutive months. In 1976, the production requirement for Group 4 was reduced to 400 in 24 months.

Reader's Guide

Group 4 regulations shaped the golden era of sports car racing and rallying. In 1966 and 1967, Group 4 sports cars were primarily entered by privateers, supporting the factory Group 6 prototypes. The 4.7L Ford GT40 Mk I competed for Group 4 class wins while the 7.0L prototypes raced for overall victories. For 1968, prototypes were limited to 3.0L, but Group 4 sports cars could run up to 5.0L, making them contenders for outright wins. An updated Ford GT40 Mk.I won Le Mans in 1968 and 1969. The category's evolution into Group 5 in 1970 and the creation of a new Group 4 for special grand touring cars—contested by cars like the Ferrari 365 GTB/4 Daytona, Porsche 911 Carrera RS, and De Tomaso Pantera—demonstrated its adaptability.

In rallying, Group 4 regulations were the basis for the World Rally Championship until replaced by Group B. Notable Group 4 rally cars included the Ford Escort RS1800, Fiat 131 Abarth, Lancia Stratos HF, and Audi Quattro. The '100-off rule' allowed cars to be homologated as Group 4 variants of Group 3 cars by producing only 100 bolt-on option kits, though this rule was deleted after 1975. Group 4's legacy lies in its balance of production requirements and performance, enabling iconic machines to compete at the highest levels.

Did You Know?

• The minimum production requirement for Group 4 sports cars was reduced from 50 to 25 units for the 1969 season.
• The Porsche 917 was built in a run of 25 cars specifically for Group 4 homologation in April 1969.
• The '100-off rule' allowed Group 4 homologation of a car by producing only 100 bolt-on option kits, not complete cars.