I have owned the above car for a few years. (106,000 miles) The trany seems to have a whinning sound inside and out when driving. Almost like your driving a slot car
The transmission was overhauled about 10,000 miles ago and a larger cooler installed to keep it from going into limp mode. The noise remained after the overhall but I am not sure if it's normal or not for BMW's as this is the first one i've owned ...