What will take the permanent water marks off glass

try using newspaper instead of paper towel, it takes a little effort.

I have used Bartenders friend. It is a powder cleaner like comet but it does not scratch. I have not used it on my car window, but have used it on the glass shower doors and it does a much better job than anything else I tried. You can find it in the cleaning section at Walmart for about $1.50. I would of course try it on a small area first but I think you'll be happy. Good luck.