Mealey's (December 1, 2021, 7:26 PM EST) -- WASHINGTON, D.C. — A final rule on greenhouse gas emissions and fuel efficiency standards for medium- or heavy-duty vehicles does not give the U.S. Environmental Protection Agency and National Highway Traffic Safety Administration (NHTSA) the authority to regulate trailers pulled by tractors because trailers are not self-propelled, the District of Columbia Circuit U.S. Court of Appeals concluded Nov. 12. It therefore vacated all portions of the rule that apply to trailers....