Very, very good idea. But maybe not GTA4, GTA3 only has 50 cars and VC has about 100 and SA has maybe 500 excluding freight train and Brown Streak commuter?
Other cool games with cars are:
FlatOut
GTA series
Need For Speed series
Burnout series
Midnight Club 3:DUB Edition/REMIX
Ford Racing3
Ford vs. Chevy
Project Gotham Racing 1, 2 and 3