As per the 2011 Motorsport Ireland Yearbook – Appendix 81. See the Technical Requirements section for further information and downloads.

3. CHAMPIONSHIP CLASSES.
3.1. Definitions.
Production Saloon: Bodyshell as per originally manufactured. GT & Sportscar: Production and non production GT and Kit Cars. Turbo/supercharged: CC x 1.7 applies to classes 1, 2, 3A, 3B, 6, 8, 9.

3.2. Classes.
(1) Production saloons up to 1400cc including Mini’s with removable front section.
(2) Production saloons up to 1650cc.
(3a) Production saloons 1651cc to 2050cc, GT/Sportscars up to 1650cc.
(3b) Production saloons and rally cars over 2050cc, GT/Sportscars over 1650cc and 4WD Rally Cars.
(4) Classic Cars per HRCA regulations. (See Appendix 48) & FIA Appendix “K”.
(5) Formula Ford 1600 as per Ford Motorsport regulations & Formula Vee as MI appendix 45 regulations.
(6) 2050 Formula Libre. Single Seaters up to 2050cc having only one camshaft and Single Seaters up to 1650cc with two or more camshafts.
(7) Libre Unlimited and all other 4-wheel drive cars.
(8) Rally cars up to 1650cc.
(9) Rally cars 1651cc to 2050cc.

Subject to sufficient entries these classes must apply to all Championship events. The organising clubs may include extra classes or amalgamate classes, subject to the approval of the Hillclimb/Sprint Committee.
Rally cars must run “Rally Ready” – to include tyres, seats etc.