No explanation yet for California Prius claim

WASHINGTON (Reuters) - Safety investigators have found no evidence so far to support or disprove a California motorist's claim his Toyota Motor Corp Prius sped out of control on its own, and cautioned the case may never be explained, U.S. regulators said on Monday.

The National Highway Traffic Safety Administration (NHTSA) engineers drove the 2008 hybrid in an effort to recreate the episode of unintended acceleration reported by owner James Sikes, 61, but were unable to do so, the agency said in its first statement on the analysis conducted with Toyota.

"So far, we have not been able to find anything to explain the incident that Mr. Sikes reported," NHTSA said. "We would caution people that our work continues and that we may never know exactly what happened with this car."

Sikes told police and reporters he was driving the car on a freeway near San Diego last Monday when it unexpectedly surged forward on its own as he was passing another vehicle, and reached speeds exceeding 90 miles per hour.

Police helped Sikes bring the car under control and then to a stop. The incident added a new dimension to the already charged atmosphere surrounding Toyota's safety crisis over unintended acceleration.

Two NHTSA investigators joined Toyota experts to examine Sikes' Prius. NHTSA said it drove the car on the freeway and obtained a copy of diagnostic readouts from the vehicle's data recorder.

"We are still reviewing that data to better understand what occurred with the car," NHTSA said.

The recorder, or "black box," contains snapshots of information about speed, braking, throttle position and other parameters. Officials would not say whether that analysis has produced any useful information.

Investigators, however, did say that a system on Sikes' car that enables braking to overcome acceleration when the gas and brake pedals are applied simultaneously worked properly in follow-up tests.

Police said the brakes were smoking when the officer who helped Sikes stop the car caught up to him on the freeway.

"There was very little left of the car's brakes," NHTSA said, adding that the inside front brake pads "were completely gone." The outboard pads were worn and the rotors were also damaged.

Toyota has insisted cases of unintended acceleration, when not caused by human error, were due to mechanical problems -- namely ill-fitting floor mats or a sticky accelerator pedal or both. Toyota has recalled more than 6 million vehicles in the United States -- 8.5 million worldwide -- for both causes since October.

Police have said they have no reason to doubt Sikes' report based on the heavy brake use and the observations of the officer who assisted him.

Toyota planned a news conference for later Monday. A spokeswoman had no immediate comment on NHTSA's report.

California Representative Darrell Issa, the top Republican on a congressional committee investigating the Toyota matter, said on NBC's "Today" show that "it appears as though this is not an example that would likely be credible in finding a new flaw in the Toyota system."

He was cautious about suggestions there could be some as yet undiscovered software problem acting as a ghost in the vehicle's acceleration system. Issa had a staff member on hand for the NHTSA examination of Sikes' car.

NHTSA has been criticized by congressional committees for not aggressively investigating past acceleration complaints against Toyota, including consumer reports that software-driven electronic throttles may be involved.

It has on numerous occasions examined Toyota and Lexus vehicles based on complaints similar to Sikes' and never found a problem with the acceleration system -- outside of floor mats, records show.

This was the first time a Prius, the world's best-selling hybrid, has been the focus of such scrutiny, raising the potential stakes for Toyota.

Toyota in February recalled 2010 Prius models for braking problems, and Sikes' model was among those included in the October floor mat recall, but NHTSA did not mention them in its report on its examination of his car.

Toyota steadfastly maintains its throttles are sound. Experts have said that unintended acceleration industrywide is a relatively rare occurrence and likely difficult to pinpoint.

Authorities believe floor mat problems in Toyota and Lexus vehicles are linked to five U.S. crash deaths since 2007, and they are investigating 47 other fatality reports over the past decade that allege unintended acceleration.

(Reporting by John Crawley; Editing by Derek Caney and Maureen Bavdek)