Volatile substances in the polymeric materials used in vehicles condense on interior window surfaces. The revised GM9305P test procedure provides temperature and time conditions that better simulate the volatilization/condensation process in vehicle interiors. The GM9305P test was modified by altering the sample temperature, raising the condensate collection plate temperature, and delaying the post-test gloss measurement to 16 hours. The chemicals collected and measured in this revised window fog test match those found on interior vehicle windows. This research is based on extensive chemical analyses by gas chromatography/mass spectrometry.