The US plans to settle an agreement on vehicle efficiency standards to ensure consistent rules in all 50 states.

Donald Trump’s administration aims to bring federal regulators, carmakers and California officials together to reach a consensus on emissions levels – this would allow manufacturers to avoid having to design cars for varying regulations among states.

California, faced with the country’s worst smog, has been writing its own air quality rules since 1970.

Nine other states follow its standards – together they account for nearly a third of US road vehicle sales.

According to a White House spokesperson, the US Government has no immediate plans to challenge California’s unique authority to set its own standards.

President Trump last month reinstated a review of former-President Obama’s national greenhouse gas rules, saying they “would have destroyed” the automotive industry.

California responded by stating it won’t lower its 2025 tailpipe emissions targets and began drafting even tougher goals for 2030.

California Air Resources Board Chair, Mary Nichols, said: “California has reaffirmed our willingness to stick with the deal we made in 2012 in the interests of stability and unity.

“Unfortunately, the [automotive industry] alliance seems eager to exploit the change in the White House to slam on the brakes and roll backwards as quickly as possible.”

The head of the US Environmental Protection Agency has said Carbon Dioxide isn’t the main cause of climate change.