This is a video of the Forte Koup racing in the new Forza 3 game.
The "official" car list of GT 5 is almost 2 years old. There's wiki's and others but they're just speculation or wish lists.GT5 doesn't seem to have the Koup from the few official car lists i've seen.. But it does have the Sedona.. Forza 3 > GT 5..
Actually.. I've played GT 5.. it looks very nice.