Ha, I have this exact same noise in my car sometimes...seems to go away after a few minutes of driving. Thought I was crazy at first. I think this might actually have something to do with the fan. A few weeks ago I had parked the car in my garage and stepped out and heard the high pitched noise as I was walking away. I went back and listened closer and the noise was coming from under the hood...and the fan was still on. So maybe that's the culprit? The car was stopped so nothing like radio, engine, etc, was running. I think the fan was the only thing.
2012 BMW 550xi
- Carbon Black - Black|Hex Aluminum - M-Sport - Convenience|Cold Weather|Premium Sound|ARS|Head-up Display|Surround Camera
2009 Audi Q5
- Prestige - S-Line