BMW X1: Whistling noise from door mirror area between 40-50 mph (60-80 kph)

PROBLEM

We have a 2011 BMW X1 in for service and the customer has complained of a whistling noise from the door mirror area when driving at a constant speed between 40-50 mph (60-80 kph)
We have heard the noise on road test but we are having difficulty finding the source of the whistling noise in the workshop. Have any other X1 owners reported a whistling noise before

Yes, this whistling noise has been reported before on several BMW models produced up to 23/11/13.
The noise is due to excessive clearance between the door mirror housing and the door mirror upper cover. Remove the door mirror upper cover.
Cut a length of felt tape, available from BMW parts department, to a width of 9 mm. Apply felt tape to the indicator repeater lamp Fig.1.1.
Refit the door mirror upper cover. Carry out road test to ensure whistling noise has been eliminated.