[diirk]

The foam cannon has been pretty handy for me. I just make sure to wash early in the morning before it gets hot, rinse, then pull it into the garage to dry off out of the sun. This has worked well for me.
As for the foam cannon itself, it seems to help remove the grime where I'm pretty much just foaming the car, letting it sit for a few minutes, rinsing it off then drying it. Only the wheels are really getting any more attention than that.