I was going to tell you a solution to this, but checked in the forum first to see if there was a better way. But, TIG said what I was going to say:
I did a test where I made the yellow color in one stripe be a unique texture then filled the other stripes with the same texture, and exported again. Now I get 15 materials, and I expect the yellow stripes will show up in BeamNG.drive.
Here’s my skp and exported Collada files.
MCdonalYellow.zip (2.2 MB)