No worries...
I'm actually driving with tweaked Shift 1/2, Dirt2, GRid, F1 2010 cars & tracks in Racer. They're all different from one another, sometimes textures are too small, or models needs to be combined, for example FM3 cars LOD0 interior which I typically merge to the outside car mesh LOD1.
In 3DSim, you load/import them (mebs, pssg), do some serious filtering, delete the unwanted parts & explode parts for final dae export & finally purge the whole (mats/text/objects). I normally check visually all UVs, where it overlaps I decide what to do, etc...but that's the final part in Maya.
The fact is, tracks contains an infinity of textures, static/dynamic objects & other stuff you want in your track, so that's 1 reason why using BTB with Maya is one of the best. I normally work with the original road + terrain. The rest is added/modded by myself via custom scripts in Maya for random distribution of trees; for example.
Let me know if you have any other questions, I'll try to answer