[944boy]

Move somewhere that has soft water! :-) There is no perfect cure. There are a few devices that remove the minerals and soften the water. They are kinda expensive but might be worth it if the problem is that bad. As for towels, I find that a water blade to remove the majority and some microfibers to do the detail work seems to do well. However around here the water is so soft I could let it dry on its own without spotting.

Also make sure that your washing in the shade or when it is cool *cloudy, night, dawn* to prevent the water from drying too fast. You could also put up a pop-tent to shade the car when your washing. It sounds like a PITA but prevents the elbow grease of removing water spots. Which by the way, detailing clay takes care of those easily, but requires waxing afterward as a minimum.