My problem with this is that supercars tend to be very low to the ground. You either have to mess with their dimensions a lot to fit a blockhead, or make it really wide and cramped (like the Marussia, which I think is a bit of a mess).
I'm not saying I'd never be interested in cars like these (I like most of them) but I'll be busy with emergency vehicles and other experiments for a while before I'd do any of these.
As far as Porsche goes, I like the 944 and 911 from the '80s. How does this make you feel?