I worked for Car Craft for a couple of years, and one of the cars we used as a test mule had originally come from the Pontiac press fleet and was subsequently purchased, after its testing duties were completed, by the editor of the magazine at the time (1988). Apparently, the press fleet cars were/are made available to members of the media after their PR stints. Specifically I can't say how the sales process officially works. I do know that I wouldn't have wanted to buy any of the cars we tested during my employment--we were awfully rough on them!
Cool Vette and a nice piece of history!