DOT issues interpretive rule to narrow fuel-efficiency standards for medium and heavy trucks

The U.S. Department of Transportation, via one outlet Highway Traffic Safety Administration, issued a final interpretive rule that narrows the application of fuel-economy standards for medium- and heavy-duty trucks, asserting that the existing rules go beyond congressional authority and hinder innovative design. The rule leaves current standards intact while establishing a legal basis for future rulemaking that could further relax requirements.

The move coincides with diesel prices climbing to $5.61 per gallon, close to historic highs. Environmental advocates, including the Sierra Club, condemned the decision, arguing that more efficient trucks lower operating costs and shield consumers from volatile fuel markets. The administration frames the change as a step to prevent over-regulation of vehicle components.