Hyperactive, Toyota races the MR2 in a 300 or 500hp class (or both, I forgot), and I think the Amemiya (or something like that) base car is also just a tiny wheezer.
I do agree though, that we don't have enough players to add so many classes yet. In fact, I would say we need balanced classes with more cars in those classes.
Balancing them is the challenge... but unless you're a player that's out of touch with the design process of the game (that same gameplay dilemna - cant make too many classes), you will know that it's fair enough if each of those cars are better and worse on this or that track. If the average is equal.
edit- "you" as in anyone, not you specificaly.