I had a weird experience today. I am trying to sell my 2002 Focus Wagon, and a guy took it out for a test run on the freeway. He came back and said that the car ran great, but it had some kind of tremendous vibrating noise when running at speeds higher than 50 MPH. I had never heard it, so he took me out to show me.
The noise is mainly there when one of the rear passenger windows is open. No wonder I had never experienced it, as I never have any windows open when driving the car.
I am not sure what it is, but the noise (kinda like "chug, chug, chug") is quite severe and increases in intensity, but not frequency, as the speed is increased past 50 MPH.
I think it may be some acoustic thing, caused by air buffeting in the cargo area (the tonneau cover there was retracted, and I have not tested it with it extended). It gets to be very loud, though, and we could feel the pressure waves in our ears.
Have any of you here experienced anything like it? Any ideas?