(CNN) -- Technicians who tested a Toyota Prius after its owner claimed its gas pedal stuck were unable to recreate the same condition, according to a draft congressional memo obtained Sunday by CNN.
In addition, owner Jim Sikes' claim that the car kept going even though he slammed on the brake while his gas pedal was stuck to the floor does "not appear to be feasibly possible," said the draft, obtained from sources familiar with the investigation.
The memo, written for members of the Committee on Oversight and Government Reform, summarizes the observations of a representative present at the testing of the Prius, as well as another car "allegedly involved in sudden unintended acceleration events."
Contacted by CNN, Sikes declined to comment but said he stands by his story. He said his attorney will be making a statement on his behalf Monday.
Sikes said last week he was traveling east on Interstate 8 outside of San Diego, California, when his accelerator stuck as he sped up to pass a car.
"As I was going, I was trying the brakes ... and it just kept speeding up," he said.
Sikes said he called 911 for help as he was traveling in excess of 90 mph on a winding, hilly portion of the highway. He said dispatchers tried to talk him through ways to stop the car, but nothing helped.
Eventually, a California Highway Patrol officer caught up to Sikes and used the patrol car's public address system to instruct Sikes to apply the brakes and the emergency brake at the same time. That tactic worked, and he was able to stop the car.
The memo said that before Sikes' vehicle could be tested, technicians had to replace rotors, brakes and pads, because the pads and rotors were worn down.
David Justo of Toyota Motor Sales headquarters, described in the memo as Toyota's residential hybrid expert, said that if car's gas pedal was stuck to the floor, and the driver applied the brake, the engine would shut down.
"If the engine does not shut down, then the gears would be spinning [past] their maximum revolutions per minute and completely seize the engine," the memo said, quoting Justo. "So, in his case ... 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."
Technicians from Toyota and the National Highway Traffic Safety Administration took Sikes' Prius on a test drive and attempted to duplicate the same experience, the memo said, but were unsuccessful. A congressional staffer and another Toyota technician tested another Prius.
"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. "NHTSA and Toyota field representatives reported the same results with the 2008 Prius owned by Mr. Sikes."
"These findings certainly raise new questions surrounding the veracity of the sequence of events that has been reported by Mr. Sikes," said Kurt Bardella, spokesman for Rep. Darrell Issa, R-California, and ranking member on the committee.
Toyota recently issued widespread recalls because of problems related to the accelerator pedal in several of its auto models. One theory behind the sticky accelerators is the vehicles' floor mats. But Sikes said last week, "My mat was perfect. There was nothing wrong with my mat."
He said that before the incident, he had taken his 2008 Prius into a Toyota dealership and gave workers his recall notice but was told his car wasn't on the recall list.