U.S. officials are calling for changes to vehicle braking systems to prevent the sudden-acceleration problems that led to reports of deaths and a recall of millions of Toyota vehicles.
U.S. Transportation Secretary Ray LaHood told a congressional committee on Tuesday that safety regulators may require all automakers' new cars to have brake systems that can override the accelerator, allowing a driver to stop safely if the vehicle begins to speed out of control.
Toyota has announced it will install such systems on all of its new vehicles and several existing models.
Executives from the Japanese automaker testified Tuesday at a hearing by the Senate's Commerce, Science and Transportation Committee - the third congressional hearing in a week about the auto giant's safety problems.
Toyota has recalled more than 8 million vehicles worldwide to correct possible problems with unintended acceleration. Some experts and lawmakers believe a faulty electronic system is to blame.
Toyota's chief engineer Takeshi Uchiyamada told lawmakers the automaker is confident its electronic engine controls are not causing cars to accelerate suddenly and crash.
Senate committee Chairman John Rockefeller expressed frustration with Tuesday's testimony, suggesting that Toyota officials have not been forthcoming with information about their vehicles' safety problems.
Rockefeller also criticized the National Highway Traffic Safety Administration and its parent agency, the Transportation Department, for not acting swiftly enough to address consumer complaints.
The U.S. Department of Transportation said Tuesday it is now investigating 52 deaths over the past decade for possible links to unintended acceleration in Toyota vehicles.
Yoshimi Inaba, the president of Toyota's North American arm, said former U.S. Transportation Secretary Rodney Slater has been picked to head an independent quality-control review panel.
Toyota President Akio Toyoda has apologized before a U.S. House committee for not doing enough to fix safety problems that prompted a massive recall.
Some information for this report was provided by AFP, AP and Reuters.