This thread is so funny, i have the same issue, it a cross between a squeak and rubbing / vibrating noise.
I have got my girlfriend to try tell me where its coming from. First i thought it was the leather arm rest, which does make a squeaking sound when pressing it.
After trying a few things, i think it the piece of plastic that runs down the side below the glove box. If you open your door, where you can see the half moon shape piece of plastic where the fuse box is in European cars, below that is a long piece which goes the floor. I pressed that in hard all the way down, it went away......
But it has since come back, so im thinking some hot glue and something similar is in order, as it drive me mad....I hate rattles in the cabin.