The US Department of Transportation published a final rule Monday that rolls Corporate Average Fuel Economy (CAFE) standards back to levels not seen in more than a decade. The new target is just 34.9 mpg by model year 2031 — below the 40.4 mpg the first Trump administration set in 2020, and far below the 46.7 mpg for model year 2026 that rule replaced.
The outcome was expected. Transportation Secretary Sean Duffy declared Biden-era efficiency rules dead in January 2025, and that July his department said it would not fine automakers for exceeding CAFE limits, retroactively to 2022.
Three structural changes matter more than the headline number. From model year 2028, emissions credits — the mechanism that let manufacturers trade efficiency surpluses — are gone. Plug-in hybrids and EVs will no longer count toward an automaker's fleet average, removing the arithmetic that let a single electric model offset a fleet of thirsty trucks. And from model year 2030 the light-truck loophole narrows: DOT says classification criteria will "reflect each vehicle's intended use accurately," flipping today's roughly 70 percent light-truck / 30 percent passenger-car mix toward the reverse.
The department argues credits discouraged investment in cleaner engine technology. Critics see a different trade-off. "Lowering these standards now, when so many families are already struggling with rising transportation costs, will only make things harder for them," said Albert Gore, executive director of the Zero Emissions Transportation Association, warning that a lower bar risks leaving American industry behind in the global auto market.
For context: the Obama administration's 2012 rules pointed toward 54 mpg by 2025. The industry never got there, and the ensuing cycle of standards, credits and litigation has become one of the most predictable features of US climate policy.
