This is a mode currently available for Carmageddon: Reincarnation. CarMODgeddon currently has support for level, vehicle and wheel mods. To put your mods in Carmageddon: Reincarnation you'll need to create a folder called "CarMODgeddon" within your game folder. Inside this you'll also need to create the following folders:
Levels, all cars that aren’t DLC, and all rims/skins are unlocked whilst in CarMODgeddon mode. Career, save games, stats, leaderboards are all disabled.