I think that a balanced car set is still possible, but we need to divide the Supercars class into two or more sub-classes, because there is no realistic way a Honda NSX can go toe-to-toe with a Koenigsegg CC8S.

After dividing the cars up according to real-world performance, we can then tweak the tire parameters on a car-by-car basis to improve cars that are too slow in a given class. So we can still have the real chassis, engine, and aerodynamic values, it is just that tires might be upgraded so that all cars in each class can compete equally.

If we do divide the cars up, this is my proposition for what cars fall where -

Production B - Common super sports cars.
- Murasama NSX
- Kanagawa Z35 GTS
- Boxer 96 (N/A)
- Spirit 300

Production A - Common "true" supercars.
- Boxer 96 (Turbo, or GT3 road model)
- Sector P4
- Taipan GSR (can be found on the community forums)
- Toro Yellinho
- Lynx 220

Production S - Hyper supercars.
- Kongei KK8S