The head of Toyota has blamed the Japanese carmaker's pursuit of rapid growth for slipping safety standards that have led to recalls of millions of cars around the world.
In written testimony released on Tuesday, a day ahead of his appearance before a US congressional panel, Akio Toyoda said he was "deeply sorry" for accidents caused by problems with Toyota vehicles.
"We pursued growth over the speed at which we were able to develop our people and our organisation, and we should sincerely be mindful of that," he said.
"Quite frankly, I fear the pace at which we have grown may have been too quick."
Toyoda is expected to face tough questioning on Wednesday from US lawmakers investigating his company's handling of customer safety concerns and its series of recalls over potentially faulty accelerators and braking systems.
"The most important thing is that we lost sight of the customer"
President Toyota North America
His apology came as the head of Toyota's US operations said he could not guarantee that fixes being applied to millions of cars would completely eliminate all potential problems.
Speaking in Washington before a separate congressional panel on Tuesday, Jim Lentz said about 70 per cent of complaints related to unintended acceleration remained unexplained.
Lentz also echoed Toyoda's comments that the carmaker's growth had come at the expense of safety.
"I think we outgrew our engineering resource," he told the hearing. "And the most important thing is that we lost sight of the customer."
Later, speaking to reporters, Lentz said many lessons had been learned from the crisis and big changes were planned for the firm.
Al Jazeera's John Terrett reports on US inquiries into Toyota's handling of recalls
"We are going to be a much more transparent company in the future," he said.
"So if someone in the company doesn't want to be transparent or if someone in the past has concealed things then, yeah, maybe they have to go."
Also on Tuesday on the first day of congressional hearings into the Toyota recalls, the driver of a Toyota Lexus involved in a 2006 incident where her car apparently accelerated to 160kph gave an emotional account of the incident.
Holding back tears Rhonda Smith recalled placing what she thought would be her last telephone call to her husband as her Lexus ripped forward on a highway.
"I knew he could not help me, but I wanted to hear his voice one more time," she said.
Smith accused Toyota and the US National Highway Traffic Safety Administration (NHTSA) of ignoring her belief that the car's electronics were to blame.
"Shame on you, Toyota, for being so greedy. And shame on you, NHTSA, for not doing your job," she told a panel of the House Energy and Commerce Committee.
|Acceleration problems with Toyota cars have been linked to at least five deaths [EPA]
Speaking to the same panel, Ray LaHood, the US Transportation Secretary told lawmakers that he had found Toyota's Japanese executives "safety-deaf" when he took office last year but that he believed the company had since charted a different course.
Nonetheless, he said, his department would conduct a "complete review" of the electronics on Toyota vehicles.
This week's congressional hearings come as Toyota faces a subpoena for dozens of internal company documents from a US federal grand jury investigating whether there is sufficient evidence for criminal charges related to the defects.
Unintended acceleration problems with Toyota vehicles have been linked to at least five US deaths, with another 29 fatal crashes being examined by US authorities.
In Japan meanwhile politicians expressed growing worries that the impact of the recalls and the investigations into Toyota could have a lasting impact on Japan's image abroad and its ability to pull its economy out of recession.
"It's a matter of safety and quality, so it is important for them to gain the understanding of the American people and work to rebuild trust," Hirofumi Hirano, Japan's Chief Cabinet Secretary, told a news conference on Tuesday.
"The fact that there was a fault in quality must be accepted gravely."