In my 911s I have always used a holder that screws into the tow hook. I would wager the same would work for the 5 series.

http://f10.5post.com/forums/showthread.php?t=740160

http://www.usmillworks.com/bmw_front..._tow_hook.html

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Current: 2012 M-Sport 550i X-drive Dinan Stage 2

Gone but not forgotten: 2007 911 Turbo, 2005 911 Carrera S, 07 BMW M Coupe, 07 335 XI, 05 Mercedes R500