I have a 2016 75D. When the speed reaches between 46 and 52 mph, there is a high pitched (and very annoying) whine very noticeable inside the car. The local facility had the car for a week last year and replaced the front motor. Said that the problem is 'common' and that is 'just the way it is'. I find this explanation just a bit hard to swallow as the loaner X didn't have this sound and I am not aware of others having the same issue. So this forum seems to be the place to ask if others have the same issue? Just as an add-on, the audio system is off and I don't believe that the sound is coming through it.