Well, the mystique IS a 6, and the contour a 4... maybe you just haven't really seen enough speed in the tour to notice any wind?
LOL
Seriously, though:
Have you checked your windshield wiper cowls for loose screws, or missing covers?
Perhaps its NOT at the windshield (all around, as you say).. perhaps you are just hearing an ambient noise that is hard to pinpoint? (wheel well liners undone and catching wind. radiator support cover (on the bottom).. etc.
Ray
