Has anyone ever heard of steam washing the exterior of the car? A local mobile detailing service offers this. They claim its the most effective way of cleaning without leaving marks.
Agreed.I'd be vary wary of anyone claiming a scratch free wash without water. Firstly, there will never be anywhere as much lubrication with water vapour and a damp cloth as with generous amounts of soapy water and a plush wash mitt. Secondly, in that picture the cloth being used is nowhere near plush enough for safe use on paint (there's no context for the photo though so can't really judge). Thirdly, on anything more than a lightly dusty vehicle the amount of time taken to properly blast off the dirt from every square inch of paint would make it very time consuming and therefore much more expensive than a normal foam + 2BM wash. Sticking with that point, at the proximity necessary to actually blast dirt off the paint effectively, the temperature of the vapour would be enough to strip any wax or polymer sealant. There are countless other reasons why steam cleaning a dirty car is much more likely to instil scratches and this is why you'll never see any of the true pro's doing it. In summary whilst it is a novel way of cleaning a car for some, I can 99.99% guarantee that it will scratch your paint no matter how safe they claim to be.