The real car was a full on tube chassis but it was nothing that was production. It was build to a better degree than this one.
Some of the stunt cars were on VW chassis to jump.
I never got what if anything was Fieto based on any of these. I imagine they may have cobbled up a few parts from a Fiero but to this point I have not seen proof.
I was around the original car PPG had and it ran well but was still a show car. No Fiero in that one.
Dodge did build a mid engine prototype that gets mistaken for a Fiero. I think that is what this car was leading to. It was more production but it was never finished. Hemings had photos a while back.