Updated

Ford Motor Co. plans to fix 17,600 Mercury Milan and Ford Fusion gas-electric hybrids because of a software problem that can give drivers the impression that the brakes have failed.

The automaker says the problem occurs in transition between two braking systems and at no time are drivers without brakes.

The decision to fix the 2010 model cars came after a test driver for Consumer Reports magazine experienced the problem as he was driving a Fusion Hybrid.

Ford spokesman Said Deep says braking power seems to drop away as the car makes a transition from regenerative brakes to the conventional system. The Ford hybrids have regenerative brakes, which capture energy from braking to help recharge the battery, in addition to a conventional system that stops the car using hydraulic pressure.

Deep says Ford will notify the car owners to bring their cars in for a software fix. He said there is no safety problem with the cars. The automaker called the repairs a "customer satisfaction program" and said it was not a full-fledged recall. Deep said Ford reported the problems to a U.S. safety agency, the National Highway Traffic Safety Administration.

The move comes on the same day that NHTSA began an evaluation of braking problems on the 2010 Toyota Prius hybrid. With the Prius, antilock brakes can fail momentarily while the car transitions between its gasoline and electric motors.

Ford told dealers about a fix on Thursday. They already had the software to repair it in case it came up, Deep said.

He said Ford did not notify all the owners before Consumer Reports found the problem because the number of problems was small.

"We're taking this action proactively to kind of address some of the customer problems we've seen," he said.

The software fix changes the pedal feel so it doesn't drop, he said.

The cars were built before Oct. 17, 2009. For models built after that date, Ford fixed the software at the factory to change the feel of the pedal, Deep said.

Jeff Bartlett, Consumer Reports' deputy editor for online autos, said one of the magazine's most experienced test drivers braked while approaching a curve in a Fusion hybrid last month, and the brake pedal dropped about an inch.

"They didn't react the way he expected," Bartlett said. "He perceived it to be a brake failure of some kind."

The driver coasted to a stop and shut off the engine, and when he restarted it, the brakes worked normally, Bartlett said.

Consumer Reports notified Ford, which responded quickly to evaluate the problem, Bartlett said.