You know that many of Japan's heavyweights dominate GT500, but GT300 is pretty diverse. I'll agree that rally cars don't make good road racers, but a race car is a race car is a race car. Maybe the only real exception to the rule would be the Lancia Delta. If you raced the HF Integrale Rally Car in GT3 or the Delta S4 in GT2, they make for great road racing cars, not to mention tearing up the rally scene.
Anyhow, GT300 seen the Mosler Raptor MT900R, Chrysler Viper GTS-R, a Honda NSX, the Mazda RX-7, the Toyota MR-S, Nissan Silvia, Toyota MR2, a reborn Toyota AE86, Toyota Celica, Subaru Impreza, and (breathing)... case proven. Diversity in GT300. I think the Mosler Raptor NEVER won a race in GT300, though it led its first race at Suzuka in 2003 (set me straight if I'm wrong). The Vemac would be very wonderful to have in GT4. If you've ever seen pictures of the JGTC featuring this car, this machine looks like it should be racing Le Mans or something. It looks very much like the GT race cars I enjoy, the ones in the mold of the Lotus Elise GT1. If it were in GT4, you'd be in for a treat.