Wash your car. Dawn dish soap will work. I have this problem too, really hard water. I don't always move the car when I use the sprinklers. Another option is to go out and wipe the car down after the sprinklers have completed their cycle.
Do you mean remove the spots?
This article should help: https://1z-usa.com/pages/how-to-remove-hard-water-spots
My name is Linda and my "go-to" cleaning product for hard water is always vinegar. I mix equal parts of vinegar & water then add a quick squirt of Dawn - just a few drops is fine. Use this to wash the car, then polish those spots away. :) Wishing you the best.