WARNING: This page is about a different car, the 2013 BMW 550i GT, 2012 BMW 550i GT, 2011 BMW 550i GT, and 2010 BMW 550i GT. However, it is still accessible from the selected car via links, so may be relevant.
Bend wire end approx. 10 mm and insert in notched tip.
Pierce wire starter with uniform pressure through adhesive bead, wire end (bent part) must be positioned on window glass.