WASHINGTON — Toyota said it had fixed about 3.7 million vehicles in the United States as part of its massive safety recalls.

The world's largest automaker said in a progress report Monday that it had aggressively responded to safety problems at the urging of its chairman, Akio Toyoda, and top company officials.

Customer complaints about unintended acceleration made to its consumer hotline have fallen considerably since April. The automaker said it was expanding the role of engineering teams created to investigate problems with unintended acceleration to include other problems raised by owners.

And Toyota officials said they had reviewed 4,200 vehicles in which owners alleged problems with unwanted acceleration and did not find any link to electronic problems — a possible culprit that has been raised by safety advocates.