WASHINGTON — Toyota Motor Corp. faces more questions from Congress over its troubled safety record when top company officials testify today at a Senate hearing on the automaker's huge worldwide recall of 8.5 million vehicles.

The Senate Committee on Commerce, Science and Transportation will hold the third congressional hearing in seven days on whether Toyota and federal safety regulators acted swiftly enough to deal with cases of sudden unintended acceleration of the Japanese automaker's cars and trucks. Three Toyota executives and Transportation Secretary Ray LaHood are among the witnesses expected today.

Toyota President Akio Toyoda pledged last week before the House Oversight Committee to be more responsive to driver complaints and safety warnings from the government. Toyoda made a similar promise to improve quality control while apologizing Monday to Chinese Toyota owners.

But the company still faces lingering doubts over the cause of the problems, which it has blamed on gas pedals that can get obstructed by floor mats or stick due to design flaws. Safety experts have said the electronic systems of Toyota vehicles could be to blame. Toyota insists there is no evidence of an electrical cause.

Toyota also said today it is repairing more than 1.6 million vehicles around the world, including the U.S. and Japan, for potentially leaky oil hoses.

The recalls have damaged Toyota's reputation and set the stage for large numbers of death and injury lawsuits amid a criminal investigation by federal prosecutors in New York, a probe by the Securities and Exchange Commission and more scrutiny from the Transportation Department.

The government has attributed 34 deaths to alleged sudden acceleration in Toyota vehicles since 2000. Since September, Toyota has recalled about 6 million vehicles in the U.S.