Originally Posted by GeorgeRa
I found attaching Velcro to MB trim plastic (PE) problematic. For my window covers Velcros are keeping covers spread and they often fell off. To remedy the problem, I purchased Velcro hook rigid disks and attached them using VHB precut circles. To further secure them so they stay put I used either short screws for plastics or short sheet metal screws. I hope this will work.
We have had similar type issues sticking things to the GM plastic panels in our Chevy Roadtrek. I took something like 6 tries to get a couple of cup holders to stick to the rear door panels using VHB. Cleaning with Gumout carb cleaner and then isopropyl did pretty will, but will damage the texture of the surface some so needs to be carefully done.
I think it is a combination of things, including the basic plastic, mold release, and appearance treatments like Armoural messing things up.
One thing that does seem to help with Velcro is to use substantially larger pieces on the hard to stick to pieces than on the matching piece. For instance the piece on the door would be a 3" circle and on the mounted piece 3/4". Adhesive peels from the edges much more easily than from the center were it can't peel (tension only), so a small dot in the middle of a big one, just large enough to hold the weight, might work much better.
You can also shave down the fuzzy side of the Velcro a bit to weaken the hold to spare the adhesive if you don't have a heavy piece to hold.