The 03 35 I had them on two years when traded, never loosened up.
The 09 35, one corner of a hatch mirror did loosen up. Added a little more tape and it has been fine.

Be generous with the tape, I did perimeters about 1.5" from edge, then strips full width about 6" apart. High quality tape and proper prep are key. Think the hatches required about $50 worth of tape from auto body supply store, the stuff used to attach side moldings to car exteriors.

Metallic vinyl decals do give the appearance of etched mirror. Next time I will stack two colors, a light silver metallic outlined by dark grey to really get the effect.

Use this stuff.

http://www.amazon.com/3M-Automotive-.../dp/B000P1ALNU

on the surface you want the tape to stick too .

I WILL NEVER COME OFF!

I guarantee it. Been a bodyman 30 years and this stuff is the bomb.
carry on.. Looks great BTW :D