The cars affected are Optima sedans built from between September 29, 2005 to June 13, 2007, and a total of 70,115 cars are involved. The problem lies with the automatic transmission which can cause the car to roll even when engage in Park.

Kia said that in some cars, the transmission shift cable may have been installed incorrectly and can become detached from the shifter. If that occurs, the car would stay in the last used gear before detachment, even if the driver moves the shift lever to the park position.

"If the driver leaves the vehicle without engaging the parking brake, there is a possibility that the vehicle can roll injure a person in its path or cause a crash," said Kia in documents filed with the U.S. National Highway Traffic Safety Administration (NHTSA).

Kia has not reported any injuries resulting from the faulty transmissions so far, and they are expected to notify affected owners this month to bring their cars back to the dealers where the problem will be inspected and repaired if necessary.