I'm a little obsessive about keeping our cars clean. I don't wash them every week but if there's a noticeable amount of dirt on them, I give them a bath.
I've been using a product called Optimum No Rinse for the last 4 years and it is fantastic. I can wash the cars in the garage using only a few gallons of water. No more dragging out the hose and having to waste gallons and gallons of water.