Clarence Ditlow, director of the Center for Auto Safety, an activist group founded by Ralph Nader, said those events show the deal was made by political appointees and not by engineers. Ditlow’s 2009 inquiry prompted NHTSA to investigate the Jeeps.

Ditlow is urging NHTSA to test the trailer hitches to see if they offer added safety. Ditlow said a hitch failed to protect 4-year-old Cassidy Jarmon of Cleburne, Texas, who died in a fire after her family’s 1993 Grand Cherokee was rear-ended by a car in 2006. The hitch punctured the gas tank, he said. According to news reports, police estimated the Jeep was hit by a car traveling 52 mph.

NHTSA’s abrupt position change even worries people who own a Jeep with a trailer hitch.

Soham Vaishnav, a pediatrician from Chicago who uses a wheelchair, had a hitch installed by U-Haul on his 2004 Grand Cherokee. But he’s still not convinced it’s safe to carry his children, ages 1 and 4. So Vaishnav and his wife are thinking of buying a new car.

‘‘There’s just not enough time after a fire starts,’’ he said.

Some owners also fear the controversy will hurt resale values.

‘‘It kind of depreciates the car’s value because people would be wary of buying them,’’ said Charles Mangan, a recent college graduate from South Carolina who is moving to New York City. Mangan hopes to sell the 2004 Grand Cherokee he bought used four years ago. His SUV isn’t part of the recall, but he’s thinking of paying to get a trailer hitch installed.