I would probably go with the sound deadening panel.
I'm not familiar with the S-series, but my ML had a real bad problem with the greasy gunk on the drivers side front and rear windows. Turned out to be the glue residue from the sound deadening panels that had partially come off on both panels.
That sound deadening material may have partially lost contact with the panel, so it is free to "flutter" about with the wind turbulence. When you roll the window down, the back of the material is somewhat "glued" to the window, so it stops moving. When you roll the window back up, the glue is dragged along the window, and that is what you are seeing.
Not sure how you came up with "wheel bearing" as that wouldn't matter whether or not your window was up or down...
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car
Last edited by G-Benz; 10-17-2001 at 10:40 AM.