All 135 Class 4-JNR - Standard Cars up to 110 BHP Junior Drivers 0 Class 4-STD - Standard Cars 2 Class 4-MX5 - Road Cars - MX5 Cars 0 Class 4a - Road Cars - Series Production up to 1400cc 5 Class 4b - Road Cars - Series Production 1401-2000cc 10 Class 4c - Road Cars - Series Production over 2000cc 4 Class 4-4WD - Road Cars - Series Production 4WD of any engine capacity 2 Class 4d - Road Cars - Specialist Production, any capacity 8 Class 5 - Modified Cars - Limited Production Marque Sports Cars up to 2000cc 0 Class 6 - Modified Cars - Limited Production Marque Sports Cars over 2000cc 2 Class 7 - Modified Cars - Series Production up to 1400cc 4 Class 8 - Modified Cars - Series Production over 1401-2000cc 4 Class 9 - Modified Cars - Series Production over 2000cc 0 Class 9-4WD - Modified Cars - Series Production 4WD of any engine capacity 2 Class 11 - Modified Cars - Specialist Production Cars, any capacity 1 Class 13 - Historically Interesting Cars, pre 1972, any capacity 7 Class 14 - Classic Clubman Cars, Ford Engine, up to 1700cc 2 Class 15a - Sports Libre Cars up to 1400cc 2 Class 15b - Sports Libre Cars 1401-2000cc 2 Class 16 - Sports Libre Cars over 2000cc 0 Class 16a - Rally Cars 3 Class 17 - Racing Cars up to 500cc complying with the eligibility rules of the 500 Owners Association 3 Class 17a- 500 Owners Association - Other Cars 0 Class 18 - Racing Cars up to 600cc 3 Class 19 - Racing Cars over 600 cc and up to 1100cc 10 Class 20 - Racing Cars over 1100cc and up to 1600cc 3 Class 20a - Formula Ford Racing Cars manufactured pre-1994, Kent Crossflow engines only. Pre-1994 rules apply 5 Class 20b - Racing Cars built up to 1985 0 Class 21a - Racing Cars over 1600cc and up to 2000cc (Normally Aspirated) 2 Class 21b - Racing Cars over 1600cc and up to 2000cc (Forced Induction) 1 Class 22 - Racing Cars over 2000cc 2 INV6 - Fairfield Motor Co. Welsh Sprint and Hillclimb Championship 1 INV10 - 500 Owners Association Speed Championship (500cc) 1 INV11 - TR Register Triumph Speed Championship 9 INV13 - BOC Fassi Classic Speed Championship 9 INV16 - BOC New Barn Land Rover Interclub Championship 10 INV18 - Downton Motor Club Speed Championship 13 INV 29 - BOC Rally Car Speed Championship 3