America's gas-guzzling automobiles were heading towards extinction yesterday as Barack Obama set strict limits on car exhaust emissions and directed producers to make a more fuel-efficient vehicle fleet. The policy requires US auto makers to produce cars and trucks that achieve an average 35.5mpg by 2016, and will reduce America's carbon dioxide emissions by 30%. "For the first time in history we have set in motion a national policy aimed at increasing gas mileage and decreasing greenhouse gas pollution for all new trucks and cars sold in the United States," Obama told state governors, including California's Arnold Schwarzenegger, car industry executives and environmentalists in the White House rose garden.