Hello! I've recently bought a Z3 2.0 2000. I love it but have a whining noise coming from what sounds like the rear end when i get to around 38 - 40 MPH. After that it disappears! Strange. I have a 12 month warranty with it but would be grateful if anyone has any ideas? It was fitted with new discs and pads about 200 miles ago. Many thanks for any replies.