Its funny because I don't see any rebarb in the parts diagrams! Now that you KNOW someome has hit your car (and ran) I wish you would change the subject header to reflect this. Just gives our cars a bad name with defects when there is clearly no defective parts.
I bet teh side egg create impact tray got crushed - when your car got hit. I believe there is a sensor for teh airbags in those side pannels too. Better call your insurance agent bc you are looking at least at a $1K repair.
www.RealOEM.com
http://www.realoem.com/bmw/partgrp.d...21&hg=51&fg=17