I have heard of this problem on the E36 but not yet on the E46 model but I will look into it. If I remember correctly, the cost associated with replacment and repair for the subframe structure were recovered by BMW but only within certain conditions- the mileage must be below 50k miles, the vehicle must have been seviced by an authorized BMW repair shop whereby all records must have been kept and no abuse or excessive strain must have occured to the vehicle (sorry if you live in NYC and happen to have hit a 2 foot pothole then your out of luck). The failure seems to have started by failure in connection plates designed too thin in order to save weight.