In my country theres only this classes:
CLASS 1 - PROType(bikes included, so you can run you car vs a super bike)
CLASS 2 - 4x4 TURBO DIESEL / petrol no LIMIT of engine displacement
CLASS 3 - Petrol TURBO +1500cc > no limit cc
CLASS 4 - petrol TURBO <1500 CC
CLASS 5 - Petrol natural aspirated +1600cc > no limit cc
CLASS 6 - Petrol Natural aspirated DE 1300 ATÉ 1600 CC
CLASS 7 - DIESEL OU T. DIESEL no limit CC
CLASS 8 - Petrol natural aspirated <1300 CC
CLASS 9 - womans - No limits for the girls
You can use Nitro, water injection, methanol, propane, etc, wherever you want