2.0 Grinding Outer Shell And Structure
WARNING: This page is about a different car, the 2013 BMW Z4, 2012 BMW Z4, 2011 BMW Z4, 2010 BMW Z4, and 2009 BMW Z4. However, it is still accessible from the selected car via links, so may be relevant.
Always replace abrasives which have already been used to treat aluminum (risk of corrosion).
Do not grind the material thin.