What have you found is the best way/product to remove these without scratching the glass, of course 
A friend washed her car last week and she has hard well water. Many spots on the glass were missed when drying and now they are a major eye sore especially when she's driving in the sun. I have to take care of it after I leave the office today.

A friend washed her car last week and she has hard well water. Many spots on the glass were missed when drying and now they are a major eye sore especially when she's driving in the sun. I have to take care of it after I leave the office today.