Its just some snow foam, used with a specific snow foam attachment on the end of my jet wash. The idea is similar to soaking saucepans before washing them so the tough stuff lifts off and its easier to wash. Much of the dirt just lifts off thus reducing the risk of scratching the bodywork when you wash it with a mitt or sponge.
I used a whole tube of autosol on the back wheels and trashed a few polishing mops with my electric drill last weekend as they were a bit furred up after being left in the garage all winter.
I would have done the fronts too but I ran out of patience. Perhaps next weekend.