I always love articles on going green! This one was interesting though. Found it from here: carwash.com
http://www.news8austin.com/content/headlines/273187/go-green—wash-your-car-without-wasting-water
The results :
¢ Self-service car washes typically use about 17 gallons per vehicle, depending on the type of nozzle on it
¢ In-bay car washes, at gas stations, use about 20 to 40 gallons per vehicle
¢ The full service car washes can use up to 60 gallons per vehicle
¢ Washing it on own, in the driveway, can take more than 100 gallons per vehicle