I have the panels on my 5er starting to weather... I was considering a full paint job, so that the panels had the UV protection of a layer of paint.. It was suggested we try a product called CostaCoat.... its a very extensive wash, and clean and 6 coats of a chemical sealer.... 6 coats to get the mill thickness required for protection....
At this point we are very happy and satisfied with the product... it took a few hours to clean and prep... but the shine is back and it looks great....
Retired Business Owner, Re-manufacturing HD Clutches, Brake Shoes, Air Compressors, Sales & Installation of PacBrake and other Industrial Friction