I've heard the same thing, that you can carry concealed a BP revolver with out a permit, but I really don't think so and I think it would be foolish to do so or open or on the seat of your car.
Even though the law and government looks at black power guns differently... in my opinion they are no different. (Actually I think the same laws or lack of for BP should be the same for modern firearms, but nobody is asking me).....
with that said, keep in mind a whole heck of a lot of folks have been maimed and killed with black powder pistols.... they are just as deadly and in many ways not nearly as 'safe' as a modern handgun.
Besides that, they are a pure pain to maintain.