I spent one month and $$$ to improve the windnoise of the W126.
1. Extra padding on the doors and WURTHed around, just so I FEEL pyschological good that a little wind can't seem through the microbes of the door metal. But seriously, more so to cover any tiny gaps that may be present, what with the panel clips etc..
2. Changing of the interior velvet felt of all four windows.
3. Changing the rubber seals on all 4 doors.
4. Realignment of the doors for maximum shutting.
5. Tightening of the doors for mximum closure.
6. Changing of boot rubber seal.
7. Padding of boot, and extra wrapping of the back panel for reduction of road noise and possible back-wind sipping in.
8. Extra seal on the windscreen.
9. Lamination of all 4 doors' windows to cut out the 0.01 % of windnoise ... and resealing of the side mirror rubbers.
Thats more or less all that was done.