Americans weigh about 24 more pounds per person than we did in the 1970s. That weight, when we're driving, has to be moved around with our cars. Multiplied over the three trillion miles driven in America each year, suddenly we need a lot of gas to move around our extra chub. If we could lose those 24 lbs and reach 1970's sizes, America would used nearly one billion gallons of gas less than we currently do.
Lose weight. You first.