The recalls have hit Toyota's image
Toyota has rejected claims that faulty electronics are behind its worldwide recall of more than eight million cars.
The company said mechanical faults with accelerator pedals and floor mats were the cause of the problems, rather than the car's electronics.
Outside studies have recently criticised Toyota's electronic safety systems.
But at a press conference on Monday, Toyota rejected those findings as not credible.
Last month, the US Congress heard from a Southern Illinois University engineer David Gilbert, who said that Toyota's electronic safety systems could be rewired to allow the car to unintentionally accelerate.
But Toyota said a review of the findings by a Stanford University expert found no "real-world" evidence of an electronic flaw.
Chris Gerdes, a professor of mechanical engineering at Stanford, said that the researchers had essentially rewired the car's electronics to create the problem - something that could not happen in real life.
"We're confident in our electronic throttle control systems," a spokesman for Toyota said.
US authorities are currently investigating reports of persisting problems in Toyotas even after they have been recalled.
Toyota said these incidents were due to poor repair work, rather than a different underlying problem.