This Snow Foam is rather good. Does an almost touch less wash, hence it's name
http://www.chemicalguysuk.com/product_p/notch.htm
The thing to remember when using Snow Foam is to rinse it really well. Spend about 10 minutes rinsing it down and use it as part of your cleaning process to get as much dirt oFf as you can before you put a mitt on the car. Get it out of all the nooks and crannies too. Lift the boot because it will gather in the sills and wipe it out and also lift the spoiler manually because it gathers in their too but DO NOT jet wash in the spoiler housing, wipe it out with a drying cloth.
Never point a jet wash directly at the car, point it at a 45 degree angle and don't stand too close to the car, keep your distance. Keep the the water moving over the car, don't keep it pointed in one place for too long. As long as you are sensible, everything will be fine.
Have fun and be prepared for strange looks from your neighbours when you start snow foaming