I recently bought this thing, very skeptical from the get-go.
The water in my town is VERY hard... I get water spots on EVERYTHING in my house and on my car, even towel drying it off.
I tried it on my dark grey 2002 Camry first. Set the car in the sun for about 2 hours (95 degrees outside) to get nice and hot. With the sun full on the car, I proceeded to wash my car by the directions of the Mr. Clean. No drying whatsoever. Stepped back and waited.
I could NOT find a single water spot anywhere on the car, and I looked. Not on the windows, not on the paint, nothing.
With this thing only costing $1 a wash in the long run for refills, I'm hooked