For me it's about getting the car as clean as possible before I do the touching wash. A really good and effective prewash foam helps me to get it cleaner. The heavy cleaning is from the PW if you are useing it to clean with. And not just wisp it around and rinse off the prewash foam. But use the water pressure from the PW to clean every part of the car as you will be doing with a wash mitt. Especially clean rinsing the nocks and crannies thoroughly with it. The foam part is not so important actually. And the benefit with foam is a longer dwell time and easier to apply than a spray bottle or pump spray bottle IMO. I always has the PW when washing my car. The use of an ordinary car soap is not effective at all for the prewash step. As it's made for being aggitated with. A video I saw when the GG Surface Wash was released and one from GG showed how to use it. Made me think at least that they have taken in what many of us do in the EU. If your car is not to dirty you could get away with a touchless wash when you useing a good dedicated prewash foam. Have not tried GG Surface Wash but just to hear about it is a step forward. Gyeon Foam and gtechnic w4 citrus foam is 2 other products that is dedicated prewash foams and good ones. The results is easiest noticeble in your rinse bucket after a wash as you would not have the amount of dirt in it that you useally have. On a well maintained vehical you almost don't see that much difference. The difference is more noticeble in the longrun then. Often your LSP is on a high water repellent level longer and you will have less contaminants when it's time for decon and reapply the LSP or polishing.
I think that one part of why prewash has not been as popular before. Is that you have a 110v electric power grid. This gets you to have a less effective electric motor than we that have 220v-240v. And PW uses and a lot of power to be effective. You are on the edge for getting the great cleaning ability from the electric PW. It's good but if you have a gas PW the difference are there on the difference in cleaning ability. Then it's also much what environment you live in and what dirt you have on the cars. I know I was recommending to switch to the 1.1mm orifice in the foamcannon when I joined the forum. That's is needed in a PW with 1.5gpm or lower. So think that many that tried a foamcannon and a smaller specs PW and a foamcannon with the standard 1.25mm orifice in it. Was very disappointed with the foam they where getting. Then when you don't have much of dedicated effective prewash foam offered and used car soap. You don't see more of a difference between clean rinsing it off with or without foam.
Some use the foamcannon to foam on the car soap when you do a contact wash. And if you like suds from your car soap you like the amount of suds/foam you get on your car with car soap and foamcannon. I personally like a car soap that has an awesome lubrication and cleaning ability. If it suds from it good but not the most important for me.
