What is the purpose of our hypermiling behaviors? If it is to save money, fine. Right now I'm paying less then seven cents a mile for my fuel. If is for bragging rights, fine- I'm averaging 59 on the computer for 17,000 miles, 56 on bought fuel. But if it is to be green and reduce total fuel usage, don't we have to consider the impact of our driving on other drivers? What does our behavior do to their mileage? Example- I'm maintaining speed/slowly decelerating on a grade, but a truck is coming behind me trying to keep his momentum. In that case, I will accelerate so that he can do so, and in so doing my total fuel savings will offset the loss in my tank. If I am in a long line of cars I will be careful to allow oncoming cars to make their left turns in front of me in order to avoid several other cars decelerating or idling behind that car- even if it costs me a little fuel. I'm sure there are other examples of how our driving habits can save more fuel than just OUR fuel.