I had a chance to try out the Ionic Clean by Homeright this weekend. This cleaning system uses de-ionizing technology, which can turn ordinary water into a more purified form for cleaning.
It comes in that airtank thing that you see here, and it comes with an attachment for your hose. When you turn the water on, you have the option of the de-ionizing (DI) water. Think of it as a soap, but not quite as potent as real soap.
You should feel free to add soap to get rid of the real spotted areas on your car, without streaks and no drying required. After you have used the DI water, you can switch to the “rinse” function for some plain and ordinary water on whatever it is that you are washing.