Waterless car washing is actually a lot safer than it sounds. The idea behind it, like any car wash, is to lift the dirt off the surface and allow the lubricants in the waterless car wash to slide the dirt off of your paint without scratching.
Here is a link to a short article I wrote about it on our blog:
http://www.inmygarage.com/?p=1394
I use our Spray-On Car Wash on my cars all the time. The car can be pretty dirty, but you just want to make sure it isn't splattered with mud all down the side. But I've done it on cars that see a week or two of commuting in the rain.
The most important thing to remember is to not use much pressure when wiping with your towel. Too much pressure will press the dirt into the paint not allowing the lubricants in the product to do their job. If you have an area where the dirt is a little more stubborn, mist with a little more product. The Spray-On Car Wash will soften the dirt and lift it off the paint. Good towels are also important. A high-loft micro fiber will be gentle on the paint and also be able to hold the dirt away from the surface better than a cotton or thinner micro fiber.
I hope this helps! Let me know if you have any questions.
~derek
