Congressional leaders joined President Bush at the signing of the energy bill.President George W. Bush on Wednesday signed into law the first increase in auto fuel economy standards in more than three decades.

The initiative was part of a sweeping energy bill that also calls for six-fold increase in ethanol production by 2022, but stopped short of rolling back lucrative tax breaks for oil companies that could have funded alternative energy development. Bush had threatened a veto if the final bill eliminated the tax incentives.

According to the Washington Post, the law requires new cars to average 35 miles per gallon by 2020, instead of the 25 mpg now required. It also includes new rules and incentives to encourage greater efficiency in light bulbs and buildings.