Just my proposal, what about:
A BMW like, front engine, rear wheel drive, atmospheric engine (Progresive without lag) about 250-280cv (something like a M3)
Nascar or similar to run ovals (Heavy and with an V8 roaring)
Something like lemans sport prototypes, aka Porsche 956-962 or similar, for endurance races (2 to 6 hours) or sprints (A silhouette like the Porsche 935 could be very interesting too) I am talking about cars in the 600-800 cv range
Clasic cars? why not (Rigid axle, carburetor, old suspension layout
They should not be real cars, just get the inspiration.