Then Data->Cars.
Select your carīs folder and make a safety copy.
After this delete GEOMETRY.BIN and TEXTURES.BIN
Now you can copy those datas from every car which you can bye at car dealer and fit in the both in your originaly folder.
I donīt know where the limits are because it doesnīt work every time. Maybe the car has to be your level or lower, maybe not. But you can try and donīt have to buy new cars. But it wonīt change optical appearence and values, just the "inner values" : accelleration, sound (top speed i donīt know
Have fun!






