1. Historic Touring Cars Today – Known as Group N not only caters for production touring and touring cars built before 31st December 1972, it also caters for Group A & C Touring Cars.

Group N is divided into three time periods defined as Na, Nb and Nc, and is unique in that individual cars are not required to have a competition history in order to be eligible.

Group Na is for production touring cars as recognised by CAMS and commercially available in Australia prior to 31st December 1957, with the inclusion of certain run-on models

Group Nb is for series production type touring cars manufactured prior to 31st December 1964 of which 100 of the particular model must have been produced (also known as Appendix J). This group is open to cars which were built and established a competition history either in Australia or overseas, provided the make and model was homologated with the FIA.

Group Nc is for touring cars of a make and model which competed in Australia between 1st January 1965 and 31st December 1972 in either the Australian Touring Car Championship or in races specifically for the 3rd Category Group C Improved Touring Cars.

Group A caters for vehicles with a competition history established in Australia and elsewhere in the period 1 January 1984 to 31 December 1992 in events run to regulations promulgated by FISA and or as adopted by CAMS for Group A Touring Cars.

Group C caters for vehicles with a competition history established in the period 1 January 1973 to 31 December 1984, in events run to regulations promulgated by CAMS for Group C Touring Cars

2. The History of the Australian Touring Car Championship

Appendix J Touring Cars was an Australian motor racing category for modified, production based sedans. It was the premier form of Touring car racing in Australia from 1960 to 1964.
The category was introduced by the Confederation of Australian Motor Sport to take effect from January 1960. Prior to the introduction of Appendix J, there had been no national regulations for touring car racing in Australia with individual race promoters applying differing rules regarding eligibility and modification of the cars being raced.

The Australian Touring Car Championship was open to cars complying with Appendix J from its inception in 1960 up to and including the 1964 title. The inaugural Australian Touring Car Championship race at Gnoo Blas circuit at Orange, New South Wales on 1 February 1960 was in fact the first race to be staged for Appendix J cars.
From January 1965, Appendix J was replaced by a new category, Group C for Improved Production Touring Cars.

In 1981 CAMS introduced the Group N Touring Cars category which was intended to recreate the style of racing which had existed under the Appendix J rules. Originally Group N was restricted to cars manufactured before January 1965; however, this was later extended to permit models produced up to the end of 1972.

Group N Touring Cars is an Australian motor racing category for touring cars built before December 1972.
The category was introduced in 1981 and was initially known as Group N (Appendix J) Saloon Cars (Pre 1965). Cars had to be series production type saloons with seating for four, manufactured prior to 31 December 1964, of which at least 100 had been produced. Mechanical modifications were permitted with the intention of emulating racing under the Appendix J regulations which were current in Australia until 31 December 1964.
The eligibility criteria were amended in 1995 to include cars built up to 31 December 1972.
Group N is currently divided into three classes.
Group Na is for cars commercially available in Australia prior to 31 December 1957.
Group Nb is for cars manufactured prior to 31 December 1964 of which 100 have been produced.
Group Nc is for cars of a make and model which competed in Australia between 1 January 1965 and 31 December 1972 in either the Australian Touring Car Championship or in other races for Group C Improved Production Touring Cars.
Individual cars are not required to have a competition history in order to be eligible.

Group C Improved Production Touring Cars
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 C Touring Cars
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

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.

Group A was a set of motorsport regulations introduced by FIA covering production-derived vehicles intended for outright competition in touring car racing and rallying
The Confederation of Australian Motor Sport had originally announced in mid-1983 that Australia would adopt Group A from 1 January 1985 to replace the locally developed Group C rules that had been in place since 1973
From 1993, CAMS replaced Group A with a new formula for Australian Touring Car racing which was originally known as Group 3A. This was initially open to five litre V8 powered cars and two litre cars (later to become known as V8 Supercars and Super Touring Cars respectively).
Group A is now a historic class, though only actual cars raced from 1985–1992 (complete with log books) are allowed to compete.