An RO system would be ideal, but way too expensive for just a couple of accounts. We toyed with running an inline water softener system, but also difficult. There are some commercial "spot free" additives you can put in your water tank, but they don't guarantee success either.
We used to do 2,000 - 3,000 cars a week for several dealers with 3 man crews (1 washer - 2 chamois). At this time of year it's almost impossible to get cold cars dry enough with a chamois and not leave streaks & spots. Besides, it's G*@ Damn cold on the hands! I suppose you could use a commercial, gas powered blower to blow off the water. The bigger challenge will be to lower your clients' expectations. Hey, it's WINTER!! I would recommend a "winter wash" program. Spray only (cold not hot) just to get off settled dirt after rain, snow, plowing, etc. Only need one guy then and you could charge A BIT less, but make more money. Temps should be 40 degrees or more. DO NOT use hot water!!! You can crack windshields and the hard water will calcify on the windows & paint and you will have very unhappy clients.
We quit doing cars over 3 years ago. Way too much motion for not enough money. Good Luck!
