The U.S. government is in full retreat from its efforts to make vehicles more fuel-efficient, which it had been prioritizing, along with state governments, since the 1970s. The latest move came on Feb. 12, 2026, when President Donald Trump and the Environmental Protection Agency issued a new rule rescinding the landmark “endangerment finding,” and reversing various emissions limits on cars and trucks. The 2009 finding stated that greenhouse gases pose a threat to public health and welfare. If the new rule stands up in court and is not overruled by Congress, it would undo a key part of the long-standing effort to limit greenhouse gas emissions from vehicles. As a scholar of how vehicle emissions contribute to climate change, I know that the science behind the endangerment finding hasn’t changed. If anything, the evidence has grown that greenhouse gas emissions are warming the planet and threatening people’s health and safety. Heat waves, flooding, sea-level rise and wildfires have onl...