Mike Michels cites 'significant inconsistencies' in Mr Sikes's account
Toyota Motor Corp says it has found no evidence to support a driver's account of a widely-publicised "runaway" Prius incident in California last week.
James Sikes said his Prius sped out of control, but Toyota said its own tests could not replicate the event.
Millions of Toyota models have been recalled after several complaints about the braking and accelerator systems.
Toyota insists that it has found no problems with its electronics, and that its mechanical fixes are sufficient.
Last week's incident raised new questions over Toyota's flagship model, the hybrid Prius.
Mr Sikes, 61, claimed his car suddenly accelerated on a San Diego freeway and that he could not stop it for some 20 minutes until a highway patrol officer helped him slow the vehicle down.
At a news conference in California, a company spokesman said the technical findings differed significantly from the account given by the driver.
We may never know exactly what happened with this car
National Highway Traffic Safety Administration
Toyota said an examination of Mr Sikes's Prius showed that he repeatedly applied the brakes some 250 times, but only lightly.
That account appears to contradict Mr Sikes's statement - backed by the California Highway Patrol - that he was frantically slamming on the brakes.
"While our analysis is not finalized, Toyota believes there are significant inconsistencies between the account of the event of 8 March and the findings of this investigation," Mike Michels told reporters.
"We're not calling him a liar and we're not judging what he did or did not do," Mr Michels was quoted as saying by AFP news agency.
Earlier in the day, federal safety regulators said their analysis of the vehicle had failed to find "anything to explain the incident that Mr Sikes reported".
"We would caution people that our work continues and that we may never know exactly what happened with this car," the National Highway Traffic Safety Administration (NHTSA) added in the statement.
Toyota already faces dozens of lawsuits that could cost it billions of dollars.
Federal authorities are examining if there are grounds for criminal charges.
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