There were single car make races before Spec II on the JPN version, as well as "class-based" races (make/model range). I'm sure we'll see this type of thing in future race updates. In fact, we somewhat already do... there's F2007 specific races (with limited tuning abilities) in the current batch.
I think this is a fantastic idea. I would also like to see this extended to online races and have the host pick which cars can be used in his race (e.g. one car, or several similar cars).
