NEW YORK (Reuters) - A U.S. appeals court on Tuesday overturned a lower court's decision to grant class certification to car owners who settled with Hyundai Motors 005380.KS and its Kia 000270.KS affiliate over the fuel efficiency of its vehicles.

FILE PHOTO: The Hyundai booth displays the company logo at the North American International Auto Show in Detroit, Michigan, U.S. January 16, 2018. REUTERS/Jonathan Ernst

In their 2-1 order, the judges of the U.S. Court of Appeals for the 9th Circuit said the lower judge had erred in concluding that common questions existed to justify a class action status.

The companies in 2013 agreed to pay $395 million to resolve claims from vehicle owners who had sued the company over misrepresenting its vehicles’ average mileage claims.

The lawsuits were filed after an investigation by the U.S. Environmental Protection Agency, which found that the companies used improper test procedures to develop their fuel efficiency data.

A 2012 restatement by Hyundai and Kia reduced the automakers’ fleetwide average fuel economy from 27 miles to 26 miles per gallon for the 2012 model year.

Vehicles included the Hyundai Accent, Elantra, Veloster and Santa Fe and the Kia Rio and Soul.

Hyundai in a statement said it continued to support the nationwide settlement. “We look forward to resolving the remanded matter as expeditiously as possible,” the company said.

Rob Carey, a Phoenix, Arizona-based lawyer who represents the car owners, in a statement said he will seek further review in the 9th Circuit to resolve the issue.

“Our settlement puts real dollars in the pockets of consumers,” Carey said. “The Ninth Circuit’s ruling sets up meaningless new hurdles to settling a class case.”

A U.S. District Court judge in 2015 gave the final approval of the class settlement. But the car owners brought five consolidated appeals, challenging class certification, the approval of the settlement and attorney fees, which they called unreasonable in proportion to the payout the class members would receive.

Lawyers representing the car owners had been awarded roughly $9 million in attorneys fees and costs, according to Tuesday’s decision.

The majority of the appeals court judges on Tuesday agreed with those arguments, finding that the lower court had failed to define a relevant class by also including owners of used cars who were not exposed to misleading advertising.

The judges said the court had failed to calculate the settlement’s value to ensure attorney fees were not excessive.

But they added that the lower court, on reconsideration, could decide to certify a class again if it first determined the agreement’s value.