For the past 32 years, fuel economy requirements for cars and trucks in the U.S. were stagnant. That all changed in December when President Bush put his signature on a new law that slowly raises gas mileage standards for cars and trucks by 40%, to an average of 35 mpg by 2020. As a result, carmakers will begin marching out a parade of new, advanced technologies to boost miles per gallon in their vehicles.