Always had that problem when I had my GXP. The motors in the G6's run hotter than normal it seems so on somedays the bottom middle part of my windshield would always fog up. Was a pain the ass
2008 G6 Gxp Street Edition
Mods:Interior LED Neon Lighting, Debadged, 20% Tint, Flowmaster 40 Series Exhaust, Res delete, Alteza black housing taillights, Spyder black housing headlights, CRAB O3 CAI, Airraid Throttle Body Spacer, Racingline Strut bar, 91 OCT WAMS Tune.
Audio:400.1 Kicker amp, 12" Kicker CVR Ported Box