I think that LFS should be something funny to play, nice to see and quite physic-realistic, but it should not seems like a sim for driving schools, with 1 or 2 cars for every class, just to show how it works.
If it is a racing sim, it must take you to a wider choice of "look" for the cars. For example, if you run a championship, you must have (near) the same performances but you can decide the shape of the car you want. If you want a mono-brand challenge, you have only to say "only XXX cars accepted!" .