You were out in XP4!!!!
pictures please! I hope
As for the Z1, I've heard of it, saw some pics and know a bit about it. I think it had sometihng around a 3 liter engine and was the only cra in the world in which the doors would roll down like the windows! (The windows rolled down normally and then the doors would follow suit) As far as I know there weren't many if none shipped to the US, but I have seen some for sale in Israel and GB.
They look okay, nothing spectacular, but the recyclabe bit is of interest. I know they made them in the early 1990's and that's about it.
As for what makes them special, I couldn't tell you, maybe it's some of the things listed above, or a combination of them or maybe it's North American ellusiveness, I only found out aobut them a couple fo years ago, you seemed to have made it a much more recent find, and I think only the true enthusiasts know a great deal about them.