Browsing through my pictures from the museum, I just realized something--the XL1 uses an evolution of the Jaray two-body form that was put into production for the first time on the pre-war Tatra cars:
But, where those earlier cars use profile taper to a point on the lower body, the XL1 does not--but it does carry over the aggressive plan and profile taper of the upper body. Contrast with a shape more reminiscent of a
Kammheck, like the first-generation Insight:
Or better yet, the third-generation Prius:
Kamm's idea was that more gentle taper of the full tail would create more interior volume and make for a more usable car. Jaray's more aggressively-tapered form only really worked when the engine was moved to the back. In fact, I'm struggling to think of an example of a production car using the Jaray form that
wasn't rear-engine.