I'm pretty sure it was entirely a cost thing. They wanted to use as much of the basic Type I platform as possible. They had a Typ III variant that had the flatter engine, and looked like a bigger, better Brasilia.

I kinda wish there was a book that had a listing of all the XP-XXX projects GM had. It'd be fascinating to see what design ideas were being kicked around.

We need to start implementing materials that allow us to reduce mass and weight which will then have a dominio effect over the whole vehicle Cars will eb smaller and lighter which means engines and fuel tanks/cells can also be smaller and lighter.