US President Barack Obama has announced plans to reduce emissions from vehicles and make them more fuel efficient.
Mr Obama said the new national standards would reduce US dependence on foreign oil and give five years of cost certainty to a vehicle industry battling to survive.
Under the new standards, US passenger vehicles and light trucks must average 35.5 miles per gallon (6.62 litres per 100km) by 2016.
Mr Obama said this would save 1.8 billion barrels of oil over the lifetime of the programme
The Environmental Protection Agency would regulate tailpipe emissions for the first time under the standards.
The US Congress does not have to approve the standards, which will be implemented through federal rules.
President Obama has made fighting climate change a priority for his administration, and Democratic party lawmakers are this week wrangling over a historic bill many hope will provide much broader guidelines for controlling greenhouse gas emissions.