Thanks! I've been thinking about this article and wondering something specific. Is there any research to show improved mpg by washing the car, and if so, how does it compare to the carbon footprint of getting the car washed? Would be interesting to know.
We emailed our answers back to Michelle and below we have the data from those answers along with updated information:
Thank you so much for contributing those questions. As far as we know, various research is from wind tests done on a car's aerodynamics. Dirt build up does interrupt the flow of air over the surface and will not be as smooth.
If you ever saw these wind tunnel tests, they have white smoke blowing over the car with the wind, so we can see the disturbances. The difference in MPGs, I do not know. Too many variables involved... the amount of dirt, design of the car, how fast you are going, and how far you travelled. However, some tests showed that due to the increased friction created by the dirt the "average" gas mileage would be around 24 miles per gallon. A clean car would obtain a higher average of 26 miles per gallon. Also a TV science show did an episode on this very topic and their conclusion was a 10% decrease in gas mileage with a dirty car.
Nevertheless, in my article I described a "hand washing" of one's car and with collected rain water. Therefore, to come out ahead with a far smaller carbon footprint, we would have to forgo the car wash using electricity and clean drinkable water.
When I was young and helping my Dad hand wash and wax his car, I complained by asking, "Why can't we go to that new automatic car wash?"
My Dad replied, "I didn't have a Car Wash when I was your age and besides, don't you want to get stronger by exercising more?"
This conversation occurred fourteen years prior to the famous "Wax on, wax off" movie quote from Karate Kid.
Bill Lauto, at GoingTrueGreen.com
International Sustainability and Energy Consultant
Contribute your comments!