Consumers who sued Ford Motor Co. lacked adequate evidence that an electronic throttle system made vehicles prone to unintended acceleration, the Fourth Circuit affirmed March 25.

Summary judgment on the would-be class claims by vehicle owners in 17 states was proper, the U.S. Court of Appeals for the Fourth Circuit said in an opinion by Judge G. Steven Agee.

The plaintiffs alleged the throttle system in 2002–2010 Ford vehicles was defective and the vehicles should have had a “failsafe” system...