I agree. There's no such thing as a good way to wash a car totally without water. You can do a good job washing a car with a hose, but you're going to need at least 4-8 gallons of water (split between two 5 gallon buckets) per car. Plus, you'll need a rinseless wash soap like QEW, DP 4-in-1, or Optimum NRWS.
Also, as already mentioned proper technique is important.