Car Rewards - Any way to change?

United States
United States
Just started playing GT4 on PCSX2 and would like to know if there is a file/cheat/program out there that randomizes (within reason) the reward cars you get from completing championships and such? I'm growing tired of only winning cars that I can't sell. Anyone know of anything?
Gran Turismo doesn't have random prize car wins out of four for Championships/Endurance Races like in GT3.