Automobile Enthusiasts

It was a multi-spray gun that had three settings, plain water, soap foam, and "rinse" water that ran through a deionizing cartridge to give totally pure water that dries with no spotting or residue. I just used a good-quality soap/wax combo and the DI rinse weekly, with twice-yearly unscented/no additive laundry detergent hand-scrubs with a buffing and pure-wax job afterwards. It was great.

If they don't make it anymore, or you don't need the hassle or expense, a good prerinse with a hose followed by a soap/wax combo is fine. Maybe a chamois dry if you don't want any spots.