Bush described the bill as “a major step towards energy independence and easing global warming”. The White House claimed it went part of the way to fulfilling promises made at the environmental conference in Bali last week. The legislation, though limited in scope, represents the biggest fuel efficiency push by the US since the 1970s oil crisis.

The new law also contains provisions to increase the use of ethanol as an alternative to petrol. Other measures in the legislation include a statutory target of a 70 per cent increase in use of energy efficient lightbulbs and improved energy efficiency targets for fridges, freezers and dishwashers. Federal buildings will also have to become more energy efficient. The reaction of environmentalists was mixed: grateful that the White House has belatedly adopted some of the policies they have been advocating but warning that the measures were too limited and not due to be implemented for years.

Stance softened

Throughout most of his presidency, Bush has disputed scientific evidence about global warming, refusing to sign up for the Kyoto treaty setting targets for reducing greenhouse gases. Over the last year, he has publicly softened his stance, acknowledging there is a crisis, though administration officials say that in private he continues to be sceptical.

The bill was passed by the House of Representatives on Tuesday by 314 to 100, with 95 Republicans supporting the Democrats. The Senate approved it last week by 86-8.

The bill was sent to the White House in a hybrid car, using a mixture of electricity and petrol.

As well as the Democratic-led Congress pushing proposals to tackle global warming, individual states, with California in the vanguard, have been putting in place energy-saving measures at variance with the Bush administration’s position.

The new legislation requires cars and light trucks to increase fuel efficiency by 40 per cent, setting a standard of an average of 35 miles a gallon by 2020, as opposed to 25 miles at present. Bush had previously opposed regulations on petrol use.

Cut in oil demand

The Democrats said the legislation will reduce US demand for oil by 4m barrels a day by 2030, more than twice the present daily imports from the Gulf. They said the fuel economy requirements will save motorists $700 to $1,000 a year in costs.

While championing the domestic industry, Bush has acknowledged throughout the year that the US has to reduce its dependence on oil imports. The legislation addresses “our vulnerabilities and dependency on foreign oil by reducing demand for gasoline and diversifying the nation’s fuel supply,” he said. He regards a switch of cars from petrol to ethanol as a way to help achieve this.