Nope. That's not needed at all. Guess you have not yet dived into the rF2 ecosystem right?
You can just create a custom skin from within the game (it copies the default skin of that car and creates a basic driver talent file) and the new GT3 have nothing more than flat DDS textures (i.e. no AO or such). The details come with other textures through the new shaders (that's what's currently not documented/made public).
Beyond that, the files are all encrypted. 3DSimEd and other tools are useless here
In summary you can create a simple template for the GT3 cars in just a couple of minutes. But the skins will never look as good as the original content because you can only use the fallback version of the shaders