To achieve success, you have buy a car in each class.
There are 23 in total.
Here is the list:
_TC-2
_Super Tourers
_TC-1 Specials
_Muscle
_Pro Trucks
_Oval Stocks
_Modified
_Super Modified
_World Time Attack
_Group 2
_Group 1
_Prototype
_Skirmish
_Classic Mini Cup
_Classic Touring Car
_Super Tourers Heritage
_F1000
_Historic GT
_Classic GT
_G7 Specials
_Ferrari Cup
_Classic Ferrari Cup
_R26