I guess they were sold out to enthusiasts accross Europe... Given that Belgium was the site of Buick assembly back in the good old days, I'd suppose (and you can confirm or deny that) that there was a small group of "regular" Buick customers (i.e. not American car freaks that would import a 1955) that slowly vanished since the ParkAve bowed goodbye. I guess once the people who bought new Buicks ran their cars to the end of their intended ownership and went elsewhere for their comfy sedans, the ownership dwindled to the "enthusiasts" group, while many of the second-hand cars found home outside of Belgium...