High pitched "humming" sound on 2007 BMW X3

Hello, I just recently purchased a 2007 BMW X3 with approximately 28000 miles on it. Upon test drive, I did not hear the high pitched (and quite loud) humming sound coming from the front of the vehicle when driven specifically between speeds of 35 to 42 miles per hour. Strangely, this noise is not audible at lower speeds or speeds exceeding 45 mph. Also, when breaking to a stop from speeds greater than 45 mph, the noise is VERY noticeable just between the speeds indicated above. I took the vehicle for a service check but the BMW technician concluded this was a trait of the vehicle's engine. I cant imagine this to be the case considering how loud it sounds and the fact that I have been unable to find any other 07 X3 owner with a similar complaint. I am quite frustrated with this and can't imagine BMW building an engine with such a flaw. I know this vehicle has transmission issues but no such problem is experienced when I drive it. Does anyone have any ideas about this and how I should handle this problem?

by in Oak Creek, WI on June 01, 2009
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1 answer 3 comments
ANSWER by , August 03, 2009
Is this car under warranty?
COMMENT by , August 04, 2009
Yes, my X3 is still under warranty. I actually identified another area BMW service center who agreed and stated something is quite wrong. Upon further review, it appears the Rear Differential required replacement. It was replaced, I do still hear a humming noise but it isnt as loud...I am currently attributing it to tire noise as they need to be replaced.
COMMENT by , October 29, 2010
Any issues with the noise and squeaking are just a service/maintenance issue I might need to check <a href="http://www.midwesternbmw.com/services.htm" target="_blank">bmw maintenance columbus ohio</a> with my. Dealer. Is it true that the warranty should cover this?
COMMENT by , November 01, 2010
My warranty did in fact cover the costs of repair however, keep in mind, it was within the warranty period which was 4 years 50,000 miles. If you arent satisfied with the service you receive where you are, it never hurts to seek out another mechanic for a second period. It definitely helped me out. Good Luck.