i have had this problem for about 6 months now. When i go over 50mph, this odd noise comes from the underside of the car. Im certain its to the drivers side, around the wheel/axle region. I aint no boffin at cars so wouldn't have a clue what could be the cause. Hmmm, wonder if just tightening the bolts of the wheels would do...? I don't do any motorway mileage, so rarely go that fast in my car (sure i rip it on the roads), but really want to find the cause of this problem.