Majuen's mod has model (.mdl) files that should link to "Tunnel_Hull.mtl". I believe he may have renamed it "Absolute_nothing.mtl", but don't quote me on that. I didn't mess around with his files.
Tunnel_Hull.mtl itself is located in the Base Game files.
Once you are in the base game file directory, the location should be the following: (res>models<material<Track<Tunnel_Hull.mtl)
Once in there, put in the code that I quoted above and this issue is history.
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Maybe I can package this fix as a mod and just release that for people who are afraid to touch the files. You gave me a good idea.
I created this topic in the chance the game is updated and my piece of code is erased in the process. Now we can all refer back to this topic for the information again if needed.