The Trump administration took a major step toward dramatically weakening an Obama-era rule designed to cut pollution from vehicle tailpipes, setting the stage for a legal clash with California that could potentially split the nation’s auto market in two. The Environmental Protection Agency on Thursday formally submitted its proposal to roll back rules that required automakers to nearly double the fuel economy of passenger vehicles to an average of 54.5 miles per gallon by 2025. The rules, which would have significantly lowered the nation’s greenhouse gas emissions, were opposed by automakers who said they were overly burdensome. A spokesman for the E.P.A. confirmed on Thursday that the agency had completed its work on the proposed regulatory rollback and sent it to the White House Office of Management […]