I've used
3M Auto Advanced Adhesive Remover to get rid of gum and other nasty stuff and it works great.
Make sure you work it before it drys.
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1972 Bavaria> 1973 3.0Si> 2013 328i> 2009 E92 M3> 2013 F10 M5: Singapore Gray over Sakhir Orange, Executive, Driving Assistance, B&O