Does Washing Your Car Improve Mileage?
Here's an interesting discussion on this question based on a claim that regularly washing your car could save you 7% on gas mileage. The discussion is much better than the blog post, and one comment hit it right on the head with, "How dirty is your car?" I tend to believe that your car would need much muck caked on before you saw even a 1% difference.
I would be happier if the Internet were less anonymous and we could see the physics credentials on the spreadsheet guy and everyone else who makes a deductive claim. Dan and I were discussing the direction of the Internet in terms of its quasi-anonymous nature just last night. This discussion could really shed light on the question if we knew who to believe.