I actually had mostly positive results using the Mr. Clean AutoDry. I think my biggest gripe was the water volume on the spotless rinse cycle. Other than that, I thought it was a pretty solid idea for a home car wash.
Also think it depends n how hard your water is in the first place. I, personally, have had no luck with it. Though, Texas has hard water, at least my place does. I think rocks come out of the hose at times.