In my first month living in Pittsburgh, I remember driving a carload of friends from school down to the [insert unpronouncable Indian name here] river to go rafting. On the way home, I realized that my fuel gauge was way below “E,” and there were no gas stations along the 50 mile drive back to civilization (Pennsylvania is weird like that… the exits are also like 20 miles apart). But the hills were just right so that I could shift into neutral and coast for a lot of the way home, so I did that, and we got back just fine. It was stressful, but kind of fun!
There’s a whole group of folks who do this all the time, competing to get the best mileage out of their cars. They never run the air conditioners, and they don’t use their brakes if they can help it. They’re called “hypermilers” — Check out this article about them!