WASHINGTON - After five months of investigating sudden-acceleration issues involving Toyota vehicles, U.S. Transportation Department officials said they have identified no safety defects other than the ones reported by Toyota: sticky gas pedals and floor mats that can entrap gas pedals, the Wall Street Journal reported. 

Speaking to members of Congress on Tuesday, Aug. 10, federal safety officials said that in more than half of the cases of sudden acceleration studied, data collected from the vehicles' "black boxes" -- or event data recorders -- indicated the driver was not applying the brake at the time of the crash. This finding suggests driver error may be at fault. 

However, officials stressed that the investigation is ongoing and may take months to finish. Thus far, though, data supports Toyota's argument that electronic defects aren't behind the incidents, the Wall Street Journal reported. 

NHTSA investigators studied 58 vehicles involved in sudden-acceleration reports. They discovered data in 35 of them that showed the brakes weren't applied at the time of the crash. 

The preliminary report doesn't specify driver error as a cause of unintended acceleration. But people familiar with the investigation have suggested that pedal misapplication -- drivers mistakenly applying the gas instead of the brake -- is a likely cause. 

In five of the 58 vehicles studied, the data recorders failed to record the conditions in the vehicle at the time of the crash. The recorders from five additional vehicles indicated that the brakes were applied early in the incident or in the middle. In one case both the brake and gas pedals were applied. In another, evidence suggested that the floor mat had likely trapped the gas pedal because braking was sustained.

Data from nine other vehicles indicated the brakes were used only in the last moment before impact. 

NHTSA restricted its review of the event data recorders to MY 2007 or later Toyota and Lexus vehicles.

These preliminary findings are likely to stir debate over the reliability of event data recorders -- an issue that has surfaced in many civil cases involving collisions. 

Toyota faces a class-action lawsuit asserting that sudden and unintended acceleration events are linked to the vehicles' electronic throttle control. In response, Toyota has issued the following statement: 

"Toyota looks forward to defending against the allegations made in the plaintiffs' consolidated complaint. Toyota has identified two specific mechanical causes of potential unintended acceleration in some of its vehicles and has moved decisively to address these issues with effective and durable solutions. Toyota rejects claims that plaintiffs suffered economic damages because of the recent recalls.

"Importantly, to date, plaintiffs have not cited a specific cause that would support their claim of a defect in Toyota's Electronic Throttle Control System, and no credible scientific theory or proof has been advanced to support this allegation. Toyota firmly believes that the system is completely safe and that reliable scientific evidence will demonstrate the safety of our vehicles in the investigations currently underway and, ultimately, to the court." 

Toyota has recalled more than 8 million vehicles globally to address the sticky gas pedal and floor mat entrapment issues.