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 N cars raced in the 2005 Biante Model Cars Historic Touring Car Series.
- Historic Groups at www.cams.com.au Retrieved on 13 November 2011
- Pedr Davis, The Macquarie Dictionary of Motoring, 1986, page 200
- National Competition Rules, 1982 CAMS Manual of Motor Sport, pages 333-335
- Historic Touring Cars Groups Na, Nb & Nc, 2003 CAMS Mannual of Motor Sport, page 8-27