I have figured out how to unlock the Oahu cars, all 5(or 6?) stores of them. In there i have purely put mods in :thumbsup:.
https://www.youtube.com/watch?v=M97RkTW0wuY
The video pretty much is a modded cars demonstration. Each car has its own brand (bmw, mini ect.) i don't know how to create new ones but just replace unused ones.