The head of Toyota Motor Corp.’s U.S. sales unit admitted Tuesday there were mistakes in the automaker’s response to complaints over problems with its vehicles but vowed in prepared testimony for the first of a series of U.S. congressional hearings to build safer cars.

Toyota Motor Sales U.S.A. Inc. President Jim Lentz also reiterated that the carmaker’s electronic throttle control system is not behind the sudden acceleration of some Toyota and Lexus vehicles, an issue thought likely to be the focus of the hearings.

“It has taken us too long to come to grips with a rare but serious set of safety issues,” Lentz said in a prepared statement made available prior to his testimony. “We acknowledge these mistakes, we apologize for them and we have learned from them.”

The congressional hearings were to kick off Tuesday morning with a session at a subcommittee of the House Energy and Commerce Committee, where Lentz and U.S. Transportation Secretary Ray LaHood were to testify.

The hearings pose a major challenge for the auto giant as it scrambles to restore consumer confidence in the critical U.S. market.

In the prepared testimony, Lentz admitted the company “failed to promptly analyze and respond” to information from Europe and the United States on faulty gas pedals. But he added that the remedies Toyota developed since then “are both effective and durable.”

“We have rigorously tested our solutions and are confident that with these repairs, Toyota vehicles will be among the safest on the road today,” he said. “We fully intend to produce even safer, higher quality vehicles in the future.”

On the electronic throttle, Lentz followed Toyota’s line that there was no defect, denying claims by some experts and the media over its role in triggering sudden accelerations.

“We have done extensive testing of this system and have never found a malfunction that caused unintended acceleration,” he said.

Toyota President Akio Toyoda, the man in the hot seat, is scheduled to testify at the House Oversight and Government Reform Committee on Wednesday.

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