Some waterless washes are in fact totally waterless, and thats not really a good thing. The petroleum based products do not allow for dilution, so higher shipping costs, also they do not take kindly to the presence of water on the cars surface(streaking). Waterbased bucket and hose free washes (B&HFW) are also much easier on the user, can clean a car that has been partially pre-rinsed(remove caked on mud form lower portions) and generally have faster acting polymers. Those with fast polymerization leave you with a surface that is less likely to streak, or leave finger marks(try it on glass, the fast ones make excellent galss cleaner, the others make glass cleaning a pain).
Another thing to look out for in a waterless(or B&HFW) is one that stays in suspension, those that require mixing prior to use to mix in the sediment that drops out of solution mostly contain some sort of filler(caolin Clay being a common one) that will hide minor scratches, while for some thats a plus, for others it,s not the desired result.
