A preliminary investigation into accidents involving Toyota cars has suggested driver error may have played a part in many of the incidents.
The US National Highway Traffic and Safety Administration is looking into cases of "unintended acceleration".
But in a briefing to Congress members, it said that data recorders of 58 cars involved in incidents suggested brakes had not been applied in 35 cases.
The NHTSA said it was drawing no conclusions from the findings.
In nine of the 58 cases, the brakes had been applied late, the note said, with both the brake and accelerator depressed in another incident.
But reviewing data recorders was only "one small part" of government efforts "to get to the bottom of unintended acceleration in Toyota vehicles," said Transportation Department spokeswoman Olivia Alair.
"At this early stage period in the investigation, engineers have not identified any new safety defects," Ms Alair said.
Toyota has recalled about 10 million vehicles globally in the past year for various problems including faulty floor mats, sticky accelerator pedals, braking software glitches and steering malfunctions.
Its reputation has come under fire, particularly in the US where it is facing hundreds of lawsuits.
Earlier this year it was fined $16m for not disclosing potentially dangerous defects, including the "sticky pedals", to regulators.
The firm did not comment on the NHTSA briefing, but it has always maintained that its tests had found its acceleration systems were sound.