Illinois Attorney General Kwame Raoul and the city of Chicago joined a federal lawsuit Friday challenging new national fuel-economy standards that are projected to require an industrywide average of roughly 34.9 miles per gallon in model year 2031. The petition asks the U.S. Court of Appeals for the First Circuit to review and set aside the National Highway Traffic Safety Administration’s rule.
Raoul is part of a coalition of 21 attorneys general, while Chicago joined several other local governments in the case. In its Oct. 2 announcement, the Illinois attorney general’s office said the coalition alleges that NHTSA violated the Energy Policy and Conservation Act and the Administrative Procedure Act by failing to set standards at the “maximum feasible” level required by Congress. Those are the plaintiffs’ allegations; the court has not ruled on them.
The amended rule covers passenger cars and light trucks through model year 2031. NHTSA’s program summary projects the 34.9-mpg fleetwide requirement and says inter-manufacturer credit trading will end beginning with model year 2028. The agency characterizes the rule as a reset that complies with federal law and gives manufacturers more flexibility in the vehicles they produce.
The dispute centers not only on the numerical standard but also on how the agency calculated feasibility and consumer impact. Illinois argues that NHTSA improperly excluded millions of electric vehicles from its baseline analysis and understated fuel costs. The state’s filing announcement says the coalition attributes nearly $220 billion in lost fuel savings to the change, a figure that remains part of the litigants’ case rather than a judicial finding.
NHTSA’s own estimates show competing effects. Reuters reported that the department projects about $1,289 less in average manufacturer compliance cost per vehicle, but more than $1,600 in additional lifetime fuel costs. The agency also projects gasoline consumption through 2050 would rise by about 4.6%, or 121 billion gallons, compared with the prior standards, while new-vehicle sales would increase.
The case will determine whether the agency adequately explained those tradeoffs and used the statutory factors Congress prescribed. Illinois residents will not see an immediate change at dealerships because the contested standards phase in by model year, and litigation can take months or longer. Still, the outcome could affect future vehicle prices, fuel use and the compliance strategy of automakers with operations and suppliers across the Midwest.
The broader legal contest includes a separate petition from environmental and consumer organizations, The Associated Press reported. That parallel case raises related objections but does not replace the state coalition’s claims or Illinois’ role in the government challenge.
Illinois is therefore pursuing a national regulatory case through state legal authority, with Chicago participating separately as a municipal plaintiff. The court’s review will focus on the administrative record and the legality of NHTSA’s methodology—not on whether one fuel-economy policy is preferable as a political matter.
