Interesting, I have a gas Honda 3100 PSI power washer, and a Vert. I was concerned the PW was too strong for the car, especially the top, but I'm wondering if a canon will step-down the velocity of the water to the point that it will make harmless suds. . . and then just PW them off, for a touchless wash. Costco has this cannon,
https://www.costco.com/Hydro-Foam-Ca...D5Io9%2FkqE%3D
I may just have to try it. . . .