Well, along those lines, 'car' just means 'carriage', so if there's a problem with calling it a car it's that it was a cart, not a seated-people-carrying device

Well, along those lines, 'car' just means 'carriage', so if there's a problem with calling it a car it's that it was a cart, not a seated-people-carrying device (not typically or in a way that would be called a carriage anyway) - not that it doesn't resemble modern carriages. (IMO.)