What do you guys use to clean the windows on your new GTO's? It seems no matter how hard I try I can't get that 'new car off-gasing grime' off the inside of my windows. I tend to just smear it around. I've tried different glass cleaners....just a dry terry towel...but there always seems to be some 'invisible' smudge that shows up a day or two later. Are my windows contaminated or am I just doing something wrong?