We all know that the GTR interiors need a little work, since they are exactly the same as the road car versions. And we also all know that the dev's "to do" list is quite long. So, I would like to suggest a (hopefully) quick fix that would please those of us who are willing to do a little legwork.
If the devs would be willing to duplicate the current interiors, so that there are two copies of each, then have LFS use the second copy for the GTR cars, we'd be able to change one without affecting the other.
For instance, right now there are two files that the XR cars - both road and GTR versions - use (XR_Interior1.dds and XR_Interior2.dds). If the devs make copies of both files (call them XRG_Interior1.dds and XRG_Interior2.dds, for instance), then have the XR GTR use the new versions. Rinse and repeat for each class of car that has a GTR version.
We could then edit the GTR interiors without affecting the road car interiors, but the devs wouldn't have to do any new texturing. We could also reskin the road cars, without making the GTR cars look even more pedestrian or luxurious.
If the devs would be willing to duplicate the current interiors, so that there are two copies of each, then have LFS use the second copy for the GTR cars, we'd be able to change one without affecting the other.
For instance, right now there are two files that the XR cars - both road and GTR versions - use (XR_Interior1.dds and XR_Interior2.dds). If the devs make copies of both files (call them XRG_Interior1.dds and XRG_Interior2.dds, for instance), then have the XR GTR use the new versions. Rinse and repeat for each class of car that has a GTR version.
We could then edit the GTR interiors without affecting the road car interiors, but the devs wouldn't have to do any new texturing. We could also reskin the road cars, without making the GTR cars look even more pedestrian or luxurious.