Are you talking a Pro Engineer model, or solid works model. If so check out mcadcentral.com it is a forum for CAD users. I've seen people list sites that have models of cars. It is also a very helpful sight, it has helped me numerous times with my modeling tasks.
Any format will work, Pro/E, SolidWorks, Solid Edge, IGES, UGS, Nurbs... I assume racing video games each have thier own indivual format. Vila