The National Highway Traffic Safety Administration has decided not to go forward with plans to require and regulate brake-throttle override systems aimed at preventing occurrences of unintended acceleration, because automakers have already addressed the issue.

(Justin Sullivan/Getty Images)

The proposed rules were in response to a rash of incidents a decade ago involving stuck gas pedals in several Toyota and Lexus models that led to millions of the vehicles being recalled and the Japanese automaker paying over a billion dollars in fines and settlements.

In one 2009 incident that gained national attention, the driver of a Lexus ES350 and three family members were killed when the gas pedal became lodged on a floor mat and crashed after he was unable to stop the car by stepping on the brake pedal.

The regulations would have required all cars to be designed so that applying the brake pedal would stop the throttle from operating and also forced the cars return to idle when the driver removes their foot from the accelerator pedal.

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According to the agency, all light-duty vehicles are now equipped with versions of a brake-throttle override system and there are still “substantial challenges” to developing objective tests, Reuters reported.

"When the technology is in widespread use now, there is no need to continue a rulemaking," a spokeswoman for the Alliance of Automobile Manufacturers said.

However, Jason Levine, executive director of the nonprofit Center for Auto Safety, said it will take years to find out whether automakers installed the systems due to the threat of a regulation or could remove them without the regulation pending.

"What we know today is that with no requirement, there is no performance standard for the throttle control system and nothing preventing it from being sold as a luxury feature," Levine said. "We can only hope a few years from now we won't see reports of crashes that could have been prevented by a required system that met minimum safety standards."

The Associated Press contributed to this report