Exactly! We had a few Impala's last year, Trannyman's old Oldsmobile, GTPLuv had her Trans AM there, so to say they are not allowed would be incorrect. Its more a matter of good people hanging out with other good people.
I think that is the heart and soul of the BGPM. Sure it would be weird to have more other makes than GP's, but obviously over the years so far with the BGPM, that has NOT been the case nor I think will it ever be.