I have heard this too. I'm wondering if it is the swaybar bushings sticking and releasing somehow as mine occurs at the transition point in the driveway where the sway bar is just being loaded.

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Kirk
Las Vegas
2016 X5 40e Mineral White/Black Dakota Leather, ZLL, ZCW, ZDA, ZDB, ZPP, multi contour seats, rear side window shades, HK stereo
2011 E90M3, 6-speed manual