Our calculations about car efficiency tend to be wildly off the mark. The Fuqua (I am not making that up) School of Business at Duke University studied it every which way and found that improving the most energy inefficient cars with ones that are even slightly more efficient saves WAY more fuel than trading in your not-so-bad Honda Civic for a hybrid. Most of us assume otherwise. The problem arises from the fact that we're talking miles per gallon when we should be talking gallons per mile. The video explains all.