Sorry, missed this. I apply it at the end, before the spot free. I used the stuff from Ryko that came with it for a few months, then switched to warsaw's Carnauba. Neither of them foam at all or provide a nice curtain. At least it has a good smell and you can see bubbles so you know it's getting applied. Not sure on cost per car. Tire/Wheel blast I call it just that. Wheel Blast. Actually it says Wheel scrub since that is what I had installed at the time, but I don't have scrubbers now. Sounds better though if you want to go that route.