Nevermind increased mileage. That will only slow down the rate of growth in our energy consumption. We ultimately need fewer people driving fewer miles. That means population control--too late for that, probably--and a whole new approach to "getting there." We need to go fewer places, stay closer to home, and we need to put more people in larger capacity vehicles, like buses and trains. Oh, and there are two more ways to get around: YOUR LEGS! Walking is a good start, and maybe the final stop for many people. But cycling is pretty effective. In fact, a person on a bicycle is the most efficient traveler of all vehicles and animals.

Of course, with the American process of building residences further and further out from centers of commerce, all of this will be pretty problematic, especially with the minimal political support it currently enjoys. For example, we are (locally, in Maryland, USA) about to build a multi-billion road that will suck up virtually all of our transportation dollars for the next few decades. And by the time it is done, people will have finally woken up to the fact that we need to drive less. At least I HOPE they will. We are fucked.