The proposed rules are expected to cover the 2027 through 2032 model years. Environmental groups and some automakers think the proposal will result in at least 50% of the U.S. vehicle fleet by 2030 being electric or plug-in hybrids - in line with a goal President Joe Biden outlined in 2021. The administration has not backed calls by California and others ban the sale of new gasoline-only light-duty vehicles by 2035.