I've been using this for sometime, makes washing the car more fun <img src="/images/graemlins/smile.gif" alt="" />
It simply attaching to a hose pipe...very foamy, you can buy refills without having to buy the hose section all the time <img src="/images/graemlins/thumbs.gif" alt="" />
Ideal for under wheel arches.
http://www.carplan.co.uk/index.cfm?product=290