Yesterday I picked up some of this at Autozone. $5. The best $5 I've spent towards my car care so far. Used it as a PRE-SOAK and it worked very well. The car had not been bathed in a couple weeks but had been exposed to snow & salt, rain and mud, so it was fairly filthy.
* Wet car down
* Spray Eagle One Car Wash in Bottle on entire auto (many squirts per panel)
* Let stand for a few
* Sprayed down pretty well with moderate light spray to loosen dirt/salt (noticed lots of suds'ng to my surprise)
* Washed via usual 2 bucket, multiple mit method
Since the stuff suds'd so much I spent lots of time rinsing down the surface not only before washing but after washing in order to minimize the likelyhood of soap film. And walla, no soap film!! The water sheeted off and beaded up very well afterward, so obviously it does not affect the wax or sealant layers (exactly as advertised).
I had been using Bug Squash for this purpose, however, not any more. BS is great on bugs, so I will reserve it only for that purpose. I encourage others in nasty weather areas to give this a try. At only $5 OTC, it's worth it.