depends how modified it is! I entered the SVD class, SV being pretty much unlimited or highly modified and the D being for over 4L capacity ( once you times your cars liters and multiply by 1.7).
type1 is pretty much standard ( exl. 4wd cars).
type2 is lightly modified, like maybe some wheels/safety gear/exhaust/suspension.
type 3 and 4 i think are log booked competition cars? with type 4 allowing race tyres(slicks im assuming)
type 5 are kit cars, replicas. dont think you can go in this one.
type 6 is time attack type cars, so im thinking pretty much the same as SV class, i dont see the difference as they dont explain it well enough, as i assume type 6 is also unlimited mods.