A U.S. federal investigation into a dramatic Toyoto Prius incident last week, whose owner claimed he experienced a sudden and unintended acceleration, said the incident could not be duplicated.

The investigation also raises questions for the driver's version of the event, according to the Wall Street Journal in its online edition on Sunday.

The investigation by federal officials from the National Highway Traffic Safety Administration (NHTSA) along with engineers from Toyota Motor Corp. found a particular pattern of wear on the car's brakes that doesn't seem consistent with the driver's story, the Journal cited three people familiar with the investigation as saying.

Driver James Sikes, called 911 on March 8 and told the operator his Prius had sped up to more than 90 miles per hour on its own, on Interstate 8 near San Diego.

During and after the incident, the 61-year-old told authorities he had used heavy pressure on his brake pedal at high speeds, the Journal said.

"But the investigation of the vehicle, carried out jointly by safety officials ... didn't find signs the brake had been applied at full force at high speeds over a sustained period of time," said the three people familiar with the investigation.

According to a separate congressional memo about the investigation, a Toyota official who was at the inspection explained that an electric motor would "completely seize" if a system to shut off the gas when the brake is pressed fails, and there was no evidence to support that happened.

"In this case, knowing that we are able to push the car around the shop, it does not appear to be feasibly possible, both electronically and mechanically that his gas pedal was stuck to the floor and he was slamming on the brake at the same time."

Kurt Bardella, a spokesman for the top Republican of the House Committee on Oversight and Government Reform, said Sunday that the findings "certainly raise new questions surrounding the veracity of the sequence of events" reported by Sikes.

"We're not saying Mr. Sikes is wrong or that he lied, we're saying that questions have arisen in the investigation," Bardella said.

John Gomez, Sikes' attorney, said the findings fail to undermine his client's story.

"I don't put a whole lot of stock in their explanation," he said. "It's not surprising they couldn't replicate it. They have never been able to replicate an incident of sudden acceleration. Mr. Sikes never had a problem in the three years he owned this vehicle."

Toyota recently issued widespread recalls because of problems related to the accelerator pedal in several of its auto models.

On Wednesday, another Toyota driver reported a runaway Prius, this one a 2005 model, which police said struck a stone wall, causing minor injuries to the driver.

NHTSA has identified 52 deaths in instances of runaway Toyota acceleration. The company has said all along that the problem is caused by mechanical, not electronic, issues.