I wonder if you could pre-soak a whole vehicle with a "bug squash" type of product (Popr Boys or 1Z) and get the same type of "no touch" cleaning benefits? They are supposed to be LSP safe. Don't know how they would work on dirt though.
I just use a foam cannon with a pressure washer. I did some eyeball testing and found the trick really I just to use a pressure washer. While pre-soaking I'm sure does help (I do it), I've fend a pressure washer will remove almost all of the "grit" on a reasonably maintained car and wheels. It remove dirt my hose won't touch.
So, why their are a lot of costly chemicals out there, most times if you have a hose you can use a pressure washer. You only really need one that is <$200.