http://www.realgpx.com - 3DEditor is the tool required. Although you'll probably have to read up on it at http://www.grandprixgames.org to understand how it works. It does the hard work for you, makes the 3D mesh etc.
I don't mind doing the 3d meshes, thats the easy part for me, its all the converting, importing, texture + shader assigning for the game that is usually the problem. I can unwrap models and add textures and shaders in 3ds Max but for games its a different cup of tea altogether. Then getting the correct loading grid position, ai race line and so on....
Aw hell, reading this thread made me install GP4 again and start getting all the mods again!
I had it years ago when it came out and was downloading all the car mods and stuff off my dial up and got it looking decnough for the crap PC I had. Now it's all alot simpler with most of the stuff being done for you and it's amazing that people are still using this game.
Off to give it all a go now and hopefully I get the car textures this time. (Only the Ferrari Renault and williams were there, the rest were pure white. Messed around with the graphics options but no change. )
how comes gp4 never works on xp? It just crashes to desktop, i can't even complete a 3 lap race. I'm on XP SP2 and i've got the 9.6 patch in??? It's so disheartening...