It said the timeline for shifting to cleaner vehicles laid out under the Obama administration is inappropriate and sets standards too high.
The environmental regulator claimed regulations set by the former President were not practical or affordable for car manufacturers, would cost consumers more and could even risk safety.
It said it has completed a review affecting vehicles to be released between 2022-25 but did not provide details on new standards.
Current regulations require new vehicles to get 36 miles per gallon in real-world driving by 2025, around 10 miles per gallon more than the existing standard.
EPA Administrator Scott Pruitt said: “The Obama Administration’s determination was wrong.
“Obama’s EPA cut the Midterm Evaluation process short with politically charged expediency, made assumptions about the standards that didn’t comport with reality and set the standards too high.”