If I did not misunderstand the point here, it is probably due to the fact that general insulation in F25 X3 is relatively poor , especially at the doors and windows. Several members had posted similar issues as you did, like easily hearing their wives talking outside the car when all was fully closed, or as in our case, more than appropriate levels of wind and traffic noise while driving. Clivem has forwarded a BMW executive's technical explanations to this in the following thread:
http://x3.xbimmers.com/forums/showth...=591028&page=6