For the last couple of week the car (S3) has developed an intermittent whine from what sounds like the back left hand side of the car. The whine is only present at speeds above 40mph, and gets louder the faster I go - This happens the majority of the time. Some of the time the whine is only audible (40mph+) when I slightly depress the throttle - and will disappear again with my foot off the accelerator. The minority of the time can't here a thing. When it's whining, weaving side to side makes no difference to the sound. Swapping the tyres front to back has made no difference. I don't need a stereo anymore as I'm driving around with the volume on mute listening out for this fecking noise to see if its getting worse. My thoughts were: Driveshaft wheel bearings sticking caliper - but I've got no vibration through the pedal. Please don't let it be the Diff! Any ideas guys?