In the discussion on opengameart.org (OGA)[1] concerning car texture replacement, the idea of adding support for .obj raised.
.obj a format that is common in open source 3d modeling software for import/export, in contrast to the currently used .ase format.

[1] http://opengameart.org/comment/9629

This would make it easier to produce alternative models and/or textures.

farrer of OGA writes:
It should be much more easer to write a .obj importer, shouldn't? (.obj files are very simple, by the way).
As far as I've looked at trigger code, it's just a matter of writting a loadOBJ function at PModel, on "src/pengine/model.cpp" (declared at "src/pengine/render.h"), populating its internal PMesh according to the loaded values (and switching between loaders at PModel contructor, based on file extension) - could use loadASE as reference.
Unfortunally, I'm somewhat busy right now... I'll try it latter, if nobody does it first (and if it's really as easy as it seems right now on a quick look).
Any hints welcome.