I have an 02 E39 M5 with about 63k miles. Recently it started making a vibrating sound from under the hood that lasts for a few minutes before it goes away after the car warms up. The car is in the hands of my mechanic now, who just ruled out a problem with the catalytic convertor and is still trying to diagnose the issue. He's looking into whether the engine mounts might be worn from age. I was wondering if anyone here has had a similar problem and whether a diagnosis was made? Thanks in advance for your responses.