I ran into this shower while googling solar shower. This is a cool idea and I backed it on kickstarter. It is a rack mounted solar shower...mounts to any rack. Just google Road shower, and you can find it.
Here is what the site says: "With the Road Shower you can have pressurized water wherever you go. It will heat the water while you drive and will be ready to give you a high pressure hot shower at the end of the day. Hot or cold, the Road Shower has many uses from the camp hose for dishes, gear, pets, or for extra drinking water. "