I don't think it's turbo spool as it remains constant at 60 mph and goes away if I go up or down. I'll try to record it tonight and post it here. I'll check the panels too, I didn't think of that.

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2010 X5d, Space Gray, Tobacco, Premium, Tech, and rear climate packages, roof rails, spare tire, and iPod adapter.
2006 330i, Sport, 6MT