In my area, DIY car wash stations have a capability to spray the car with water that has been cleaned of contaminants using some osmosis process.
So after I wash the car I just drive 2 miles to the nearest car wash station, pop a coin in the machine and spray it with that water. Not a single water spot left after that.
The good news is that when my car accidentally gets sprinkled by garden sprinklers for instance, same treatment applies and no need to wash or wax the car again.
The osmosis process involves getting regular water into some kind of filter that removes all minerals etc in the water.
