I also have this dark spot on my M3, not as large as shown in the first picture and it is in the range of 40-60 kmh, that is why I was looking for a repair method and this seems to be to best one. The issue is the glue, it simply gives up holding and will go through stages of holding/letting go based on temperatures. This fix deletes the glue entirely.

http://www.m3forum.net/m3forum/showthread.php?t=395434