OK, I say that the Datsun/Nissans have more claim to "Z car" "the Z" "Z" any way of referring to the car that uses the letter "Z". You can also describe a Z28 as a "Z", but I would do it only in the proper context or if the person you are talking to would properly interpret the reference. If I start talking to somebody at a car show and they say "yeah, that's my Z over there" and nod in the general direction of a group of cars, I'm probably going to be looking for something with a Datsun/Nissan badge on it unless I'm at "Super Shebby Showdown".