The memo, obtained by the Associated Press, said the experts who examined and test-drove the car could not replicate the sudden, unintended acceleration James Sikes said he encountered. A backup mechanism that shuts off the engine when the brake and gas pedals are floored also worked properly during tests.

Sikes, 61, called 911 last Monday to report losing control of his 2008 Prius as the hybrid reached speeds of 94 miles per hour. A California Highway Patrol officer helped Sikes bring the vehicle to a safe stop on Interstate 8 near San Diego.

The incident happened at the worst possible time for Toyota, which has recalled millions of cars because of floor mats that can snag gas pedals or accelerators that can sometimes stick. Just hours before the incident, Toyota had called reporters to its Torrance, Calif., office to hear experts rebut claims that the company had not identified or fixed what might be causing its cars to speed out of control.

Sikes' car was covered by the floor-mat recall but not the one for sticky accelerators. He later told reporters he had tried to pull on the gas pedal during his harrowing ride, but it didn't "move at all."

During two hours of testing Sikes' car Thursday, Toyota technicians and the National Highway Traffic Safety Administration failed to duplicate the same experience that Sikes described, according to the memo written by the Republican staff of the House Committee on Oversight and Government Reform.

"Every time the technician placed the gas pedal to the floor and the brake pedal to the floor, the engine shut off and the car immediately started to slow down," the memo said.

The Prius is designed to shut down if the brakes are applied while the gas pedal is pressed to the floor. If it doesn't, the engine would "completely seize," according to the report, which cited Toyota's "residential Hybrid expert."

"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," according to the memo.

The memo did say that investigators found the front brake pads were spent.

John Gómez, Sikes' attorney, said the findings failed to undermine his client's story. "I don't put a whole lot of stock in their explanation," he said yesterday. "It's not surprising they couldn't replicate it. They have never been able to replicate an incident of sudden acceleration."