After looking at Jamizs piccies of the V6 C2, i had a gander at the creators website (on 56k, hence i cant actually tell you what they do, its in french and i cant sit around waiting for translations all day!)... but have a gander.... looks quite cool, the roof splits and stores in the boot (only takes up 10%) and the rear window, as far as i can make out, drops into the tailgate
http://www.quaidejavel.com/sport/sbarro/c4/r_pur/