That's weird, marty... you have an '05, though. Both myself and Donna have driven to the warning light and filled up right away, and we both put in about 12 gallons of gas.
tCfiend - yes. Not the rear window defroster, mind you... but the front defrosters basically run off the a/c compressor, which will lower your mileage. That's why I hate how my windows tend to fog cuz i'm wasting gas with the defroster! When you're in defroster mode, it uses the a/c to remove moisture from the air it blows onto the windshield, which unfogs them faster.