Well said!Yes, that's correct. The ethanol causes some swelling and distortion in many plastic, but it's relatively mild in HDPE. (Just enough to dislodge a tight-fitting plastic panel on a certain motorcycle!) Ducati tried to use PA6 Nylon for their tanks a few years ago. They liked it because it was: cheap, took paint very nicely (HDPE can't be painted, hence the plastic covers) and could be molded into complex shapes. Unfortunately for Ducati owners, PA6 nylon reacts much worse to Ethanol fuels and will swell enough to cause fuel pumps to leak and tank removal for servicing becomes nearly impossible. So they switched to HDPE on many of their models, just like BMW. And they still get some swelling complaints, too. The only real fix is for the manufacture to leave space under the tank covers to allow for a small amount of expansion. Too bad BMW can't figure that out.
I'm also an owner of a 2014 GS, I have been bugged by the same gap issue for a few years now. I've been able to let it go, and just enjoy the ride. Question, where can I get a workshop manual that has those instructions?The first steps are positioning the left and right covers.
Then install the centre cover.