A creak or squeak can be heard from the top of the front or rear doors. This noise is most noticeable when the windows are fully up. The noise is caused by the decay of the flocking material on the door seals. New door seals, Teflon tape, special lube, or a combination of all of these may be needed to eliminate the noise.Google+
Car Problem Reports
BMW 540i Noise From Top of Front/Rear Doors When Windows Are Fully Up
BMW 540i Problem
Average Mileage: 96,000 mi (58,000 mi - 134,000 mi)
Visitor, 2001 BMW 540i, 134,000 mi
Whistling noise from seals. Never fixed. Driver side only. Extended to sunroof too.