How have automakers improved fuel efficiency?

Change the Fuel, Keep the Change

Another good way to address fuel efficiency and oil dependency? Create a new fuel source. Alternative fuel sources, such as natural gas, ethanol and liquefied petroleum gas, are being explored and researched by the auto industry. Then there's the barely-any-fuel-at-all alternative, with Tesla Roadsters, Chevrolet Volts and Nissan Leafs that are (or are almost) entirely electric.

With stricter fuel efficiency standards like the ones President Obama has put forward being adopted worldwide, automakers have no choice but to explore ways to squeeze themselves to adopt new technology, cleaner sources of fuel and inventive designs for the future.