SAN DIEGO - Investigators are confronted with a series of nagging questions as they try to unravel the case of a California real estate agent who said his Toyota Prius turned into a runaway death trap after the gas pedal became stuck.

Why didn't the driver simply throw the transmission into neutral as officers urged him to do? Why didn't a safety mechanism activate that was supposed to cut power to the engine in such situations? And could he have made the story up in pursuit of fame and money?

Each question is getting scrutiny from the Internet-consuming public as they question the motives of the driver, a 61-year-old real estate agent named James Sikes. Some skeptics have even invoked the infamous "balloon boy hoax" in expressing doubts about the story.

No evidence has emerged to suggest that Sikes was dishonest when he called 911 on Monday to report that the accelerator of his 2008 Prius was jammed during a trip home from his lawyer's office.

Sikes and his car emerged unscathed, but the incident has been another major headache for the Japanese automaker amid questions over the safety and reliability of its vehicles.

The California Highway Patrol has repeatedly said it has no reason to suspect a hoax. It does not plan to investigate the incident or perform a mechanical inspection because there were no injuries or property damage. Investigators from Toyota and the federal government are also looking into the incident.

"There is no factual information that I'm aware of, or the highway patrol is aware of, that would discredit his story," agency spokesman Brian Pennings said Friday.

Sikes spoke to throngs of reporters twice this week about his ordeal, but he has not sought out attention or talk show interviews like others have done during their 15 minutes of fame. Pennings said he urged Sikes to speak with reporters the first time, on Monday, after the white-knuckled journey down Interstate 8 to avoid getting besieged later by the media.

And a law firm representing Sikes during the investigation said its client does not intend to take legal action against the automaker.

Doubters have asked why Sikes didn't put the car in neutral as a California Highway Patrol dispatcher and an officer repeatedly urged him to do.

Sikes said he considered going into neutral but worried he might go into reverse or flip.

"I had never played with this kind of transmission, especially when you're driving, and I was actually afraid to do that," he said Tuesday. "I was afraid to do anything out of the normal."

Toyota has said all Priuses are equipped with a computer system that cuts power to the wheels if the brake and gas pedals are depressed at the same time, as Sikes was doing.

"It's tough for us to say if we're skeptical. I'm mystified in how it could happen with the brake override system," Don Esmond, senior vice president of automotive operations for Toyota Motor Sales, said Thursday.

Dan Edmunds, director of vehicle testing at Edmunds.com, an auto information Web site, said the brake-override system worked fine on his 2004 Prius at 70 mph. He also shifted into neutral and reverse at those speeds.

"Yawn" he wrote Friday. "This was not difficult."

But Raj Rajkumar, an electrical and computer-engineering professor at Carnegie Mellon University in Pittsburgh who studies auto electronics, said the Prius could still have acceleration malfunctions even with the fail-safe system.