Depends a bit on which Volt we're talking about. The early ones has a very limited amount of power provided at higher speeds, that went from engine to wheels. Later versions could send more via this path. You never know about GM engineers but I'm pretty certain they realized that a total link via electric, wasn't the most efficient and complicated things to gain some efficiencies. The Ram and Edison guys must know something or maybe don't know as much as they think they do.
Myself, I think the pickup conversion guys are fixing to be sheared like a flock of sheep -- or maybe Rams ;-)