I have a M sport as well, and I get 4 beeps (4th one seems longest) while driving. it may be the hourly chime, but I am unsure.

Could you post some pictures of your X! I want to see the carbon black M

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2011 ///X5 M (On Order)

2009 X5 4.8 M Sport Space Gray/Black Fully Loaded

2007 GMC Yukon XL Denali Loaded and Customised