'Shame on you'
Rhonda Smith, the driver of a Toyota Lexus involved in a 2006 incident in which her car accelerated to 160kph, told lawmakers that she felt Toyota had dismissed her belief that the vehicle's electronics were to blame.
"Shame on you, Toyota, for being so greedy," she said.
The recalls over potentially faulty accelerator pedals and brakes have badly damaged Toyota's reputation for quality and reliability.
But James Lentz, the head of Toyota's US operations, repeated the company's position on Tuesday that electronic problems did not contribute to the sudden acceleration of cars.
He said stuck gas pedals in some of the company's most popular models were caused by misplaced floor mats and sticking accelerator pedals.
Earlier on Tuesday, Toyoda, the company's president, vowed to change the way the company does business.
Writing in the Wall Street Journal, Toyoda said the company had not responded quickly enough to reports about vehicle defects and promised "transparency" in the way it handles customers' concerns.
He said: "It is clear to me that in recent years we didn't listen as carefully as we should - or respond as quickly as we must - to our customers' concerns".
Toyoda, who is the grandson of the carmaker's founder, said he would take the company "back to basics", pledging that "Toyota will set a new standard for transparency and speed of response on safety issues".
His editorial appeared on the same day that the car manufacturer was presented with a subpoena from a US federal grand jury ordering it to handover documents related to the recalls.
Depending on the evidence the grand jury probe reveals, the case could lead to eventual criminal charges being brought against Toyota.
Billions in lawsuits
As well as two congressional investigations, Toyota is facing a host of US class-action lawsuits potentially costing billions of dollars that link defects in its vehicles to more than 30 deaths.
Critics, including some members of the US congress, have attacked Toyota's response to complaints of sudden, unintended acceleration, accusing it of trying to cover up defects, which also extend to the brake systems of its flagship Prius hybrid cars.
News of the US grand jury investigation came hours after the release of a document apparently showing Toyota knew of accelerator safety problems in its vehicles as early as 2007.
The internal memo appears to show Toyota executives gloating over their success in limiting a 2007 recall on some cars where the driver's foot mat interfered with the accelerator.
The memo is among thousands that a congressional committee has requested in a subpoena of Dimitrios Biller, who worked as a US lawyer for Toyota from 2003 to 2007.
Biller, who is now in a legal dispute with Toyota, said the internal company documents show the firm was hiding evidence of safety defects from consumers and regulators.