(Reuters) - General Motors ( GM ) was ordered by a federal appeals court to face a class action claiming it violated laws of 26 U.S. states by knowingly selling several hundred thousand cars, trucks and SUVs with faulty transmissions.

The 6th U.S. Circuit Court of Appeals said a lower court judge had discretion to let drivers sue in groups over Cadillac, Chevrolet and GMC vehicles equipped with 8L45 or 8L90 eight-speed automatic transmissions, and sold in the 2015 through 2019 model years.

Drivers said the vehicles shudder and shake in higher gears, and hesitate and lurch in lower gears, even after repair attempts. They also accused GM of telling dealers to provide assurance that harsh shifts were "normal."

GM did not immediately respond on Thursday to requests for comment. The decision was issued on Wednesday by a three-judge panel of the Cincinnati-based appeals court.

Class actions can result in greater recoveries at lower cost than if plaintiffs were forced to sue individually.

The GM litigation covers about 800,000 vehicles, including 514,000 in the certified classes.

Vehicles include the Cadillac CTS, CT6 and Escalade; Chevrolet Camaro, Colorado, Corvette and Silverado; and GMC Canyon, Sierra and Yukon, among others.

In opposing class certification, GM said most class members never experienced problems and therefore lacked standing to sue.

It also said there were too many differences among class members to justify group lawsuits.

Circuit Judge Karen Nelson Moore, however, said overpaying for allegedly defective vehicles was enough to establish standing.

She also said "exactly how, and to what extent, each of the individual plaintiffs experienced a shudder or shift quality issue is irrelevant" to whether GM concealed known defects, and whether drivers would have found that information material.

The court also rejected GM's argument that many potential claims belonged in arbitration.

It returned the case to U.S. District Judge David Lawson in Detroit, who certified the classes in March 2023.

"We look forward to holding GM accountable before a Michigan jury," Ted Leopold, a Cohen Milstein Sellers & Toll partner representing the drivers, said in a statement.

The case is Speerly et al v. General Motors LLC, 6th U.S. Circuit Court of Appeals, No. 23-1940.