Started noticing this sound a few months ago and it's finally starting to drive me crazy after a long road trip.
Some info about it:
- 2020 M3P (chrome trim, no octovalve)
- Happens above ~35 MPH, loudest at around 50 MPH but can still hear it at 80
- Does not correspond to HVAC fan speed, can be heard with it off
- Tone/frequency does not seem to correspond to speed
- Can be heard on very smooth pavement
- Easiest way to hear it is put AP on and put ear next to right side of steering wheel (yes, slightly dangerous)
- I thought it was related to the condenser fan (perhaps the bearings are imbalanced or the fan shrouding is rubbing) but It doesn't seem to change with fan speed (for example sounds the same with fans blowing hard after supercharging)
