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 Cars 
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.
Group C Touring Cars 
For 1973 CAMS introduced a new Group C Touring Car category to replace both the existing Group C and Group E. 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 lead to Ford Australia, General Motors Holden and Chrysler Australia ceasing direct involvement with the manufacture of high performance production cars for Group E racing. Both Ford and Holden would continue support of touring car racing, although in Ford’s case that would be limited to a single season.
The ATCC had expanded to 11 rounds in 1976 and 1977, but the 'Golden Era' often had a thin veneer as uncompetitive small engined cars bolsterred entries for many years. The low point saw just nine cars competing for the opening round at Symmons Plains in 1980, though this could be attributed to new CAMS engine emission rules which effectively banned the 1979 Holden Torana hatchback's and Ford Falcons.
The final three seasons, while seeing more manufacturer involvement from Nissan, Mazda and BMW, were plagued by parity arguments and leading teams and drivers campaigning with officialdom over technical regulations that were increasingly losing touch with the original intent of the class. In mid-1983 CAMS decided that begining on 1 January, 1985 they would replace Group C with new regulations based on FIA Group A rules which had been in place in the European Touring Car Championship since 1982, and in New Zealand since 1984.
In addition to the Australian Touring Car Championship, Group C cars also contested the following national title series:
- Australian Manufacturers' Championship, 1973 to 1975
- Australian Championship of Makes, 1976 to 1980
- Australian Endurance Championship, 1981 (this was a manufacturers title)
- Australian Endurance Championship, 1982 to 1984 (this was now a drivers title)
- Australian Endurance Championship of Makes, 1982 to 1984
Group C touring cars also contested the Amaroo Park (Sydney) based AMSCAR series from 1981-1984. The series, televised nationally by ATN-7, was restricted to cars with an engine capacity of no more than 3.5 litres in 1981, excluding the outright cars such as the Holden Commodore, Ford Falcon and Chevrolet Camaro. The restriction was lifted in 1982 and outright cars contested the series to the end of Group C in 1984.
Class structure 
Vehicles were separated into various classes based on engine capacity. The ATCC used a two class system throughout the second Group C era with the field divided into Under 2000cc and Over 2000cc classes from 1973 to 1975 and then into Under 3000cc and Over 3000cc classes from 1976 to 1984. Favourable points structures were used to encourage the smaller cars but it would take until 1986, after the abandonment of Group C, for a small class car to take outright victory in the ATCC.
The Bathurst 1000, as it became in 1973, would change several times, reflecting its roots as a race where four or five individual races held simultaneously with no outright winner promoted. The 1973 version began with cut-offs at 1300cc, 2000cc and 3000cc. For the 1977 race the under 1300cc class was abandoned and a 1600cc class was introduced for the 1979 race. After a one off cylinder based system used in 1981, the two smaller classes were removed leaving just under and over 3000c. The capacity based system was abandoned entirely for the final Group C Bathurst race in 1984 with one class for Group C cars and one for the new Group A cars to be raced from 1985.
Historic Group C Touring Cars 
An Historic Group C category now caters for vehicles with a competition history in events run to CAMS Group C Touring Car regulations in the period from 1 January 1973 to 31 December 1984. Only actual race vehicles, for which a Group C log book was issued, are eligible.
Today Group C touring cars are a spectator favourite at historic motor racing festivals, with leading drivers and cars from the era in high demand. Leading race cars are sold for hundreds of thousands of dollars, whereas less than a decade ago you couldn't pay someone enough to take away your old Group C racer, with a burgoening support industry emerging including car clubs, professional magazines, parts and car care products. The largest race meeting specifically catering to historic touring cars is the Muscle Car Masters held at Eastern Creek Raceway in Sydney. The largest museum of historic touring cars available to the public for tour is the National Motor Racing Museum, sited on the outside of Murray's Corner at the Mount Panorama Circuit at Bathurst.
- Australian Motor Racing Annual No 1, Page 37
- Historic Groups: Group C Touring Cars Retrieved on 20 March 2012
- CAMS Online manual of Motor Sport > Historic Touring Cars: Groups Na, Nb, Nc, C, A, U Retrieved on 20 March 2012