[gofast182]

Has anyone put the hood up and heard it coming from the driver's side? I mentioned it before, there's also a computer under the hood and I can hear it there, as well.

I have a background in electronics and will say it's most likely not a supplier defect, it's more likely component selection or circuit design, meaning it's an engineering/design problem.
What's more than likely happening is there's a component or components that are "ringing" (actually a technical term). Like all things there are tolerances of/for these components so if you get component A and component B on the high side of their tolerance window you can end up with it being a bit worse in one car and a bit better in another. For example an inductor, the most likely component to "ring", may have a nominal value of 200uH but have a 10% tolerance meaning it could be 220uH and still in spec. There could be a nearby capacitor with a tolerance in the opposite direction, combine those tolerances with an "optimal" length of the trace on the circuit board and boom, there's your oscillation or ringing. It could also be an audible harmonic of a processor's clock that is leaking and then being picked up elsewhere on the board. That would be a board layout or shielding issue.

The idea that a M50i or X6 will be better is misguided. These cars use the same platform, assembly line, and will inherently have a high degree of component sharing, especially things like the electronics. You could end up with one that may have favorable tolerances and not have a noticeable noise but it would be luck or coincidence.

Having sensitive hearing is a blessing and a curse. Things like this are absolutely maddening.