I know a quick web search would give the answer but I'll ask you guys/gals. It was a low number ,120, so I don't think there are many out there. So, what is it and what are the qualifications?
I used to see them quite often before the GM plant closed. They were used on manufacturer company owned cars, usually driven by executives.
I was also given a vehicle to drive for a few days displaying a manufacturer plate that was a loaner to my employer in the mid 80s. It was a factory Chevrolet (or GMC) prototype that was CNG powered.
There was at least one Corvette bearing one in the late 80s that was driven by engineers at the Stillwater Mercury Marine plant when they were developing the LT5 for the ZL1 Corvette.