what about Ultimate Stunt it looks fun and is Open Source http://www.ultimatestunts.nl/index.php?page=4&lang=en maybe you should look at. It could fill that emptiness of not having 3D racer for the GP2X.
I think unreal tournament would be awsome for the GP2x :D
i mean you can get the source code http://unrealtournament2004.filefront.com/...urce_Code;50393
and system requirements for the computer dont seem too demanding, would'nt know exactly but it seems the GP2X could possibly handle it.
so...