Group C Improved Production Touring Cars

In relation to Australian motorsport, Group C refers to either of two sets of regulations devised by the Confederation of Australian Motor Sport (CAMS) for use in Australian Touring Car Racing from 1965 to 1984. These are not to be confused with the FIA’s Group C sports car regulations, used from 1982 to 1992 for the World Endurance Championship / World Sports-Prototype Championship / World Sportscar Championship and the 24 Hours of Le Mans.

Group C Improved Production Touring Car regulations were introduced by CAMS in 1965 to replace the Appendix J rules which had been in force since 1960. The Australian Touring Car Championship was run to these new rules from 1965 to 1972, initially as a single race championship and from 1969 as a multi round series. Group E regulations defining rules for Series Production Touring Car racing in Australia had previously been introduced with effect from 1 January 1964.

The leading cars of the Improved Production era included the Ford Mustang, Chevrolet Nova, Porsche 911S, Holden Monaro HK GTS327, Holden Monaro HT GTS350, Ford Mustang Boss 302, Chevrolet Camaro ZL-1 and the Ford XY Falcon GTHO Phase III.

For 1973 CAMS introduced a new Group C Touring Car category to replace both the existing Group C Improved Production and Group E Series Production. The new Group C cars would contest both the Australian Touring Car Championship and the Australian Manufacturers' Championship, the later having previously been contested by Group E cars and run over numerous long distance events such as the Bathurst 500 and the Sandown enduro. The new Group C classification had been brought about by the media-driven 'Supercar scare' of 1972 which led to Ford Australia, General Motors Holden and Chrysler Australia ceasing direct involvement with the manufacture of high performance production cars for Group E racing. Holden would continue support of touring car racing until the end of the 1970s. Ford closed their factory team at the end of 1973 and then provided technical and limited financial support of Allan Moffat Racing between 1976 and 1978), but Chrysler ended its involvement at the end of 1972.

...
Wikipedia