The National Highway Traffic Safety Administration (NHTSA) has reported to Congress that the majority of the "black boxes" taken from recent model Toyotas indicate that driver error was the cause of unexpected acceleration in the vehicles. In 35 of the 58 cases where black box data was available, drivers did not apply the brakes before collision, which suggests that drivers hit the accelerator pedal instead of the brake. Partial braking was found in 14 cases, while both the brakes and accelerator were applied in one case. One other case was caused by pedal entrapment. Toyota officials, in a written statement, maintain that the NHTSA report confirms its findings that unexpected acceleration was not caused by electronic throttle controls. Toyota believes the problems were caused by sticking accelerator pedals and pedal entrapment caused by incompatible floor mats.

Critics, however, point out that the 58 cases reviewed are a small portion of the 8.5 million vehicles recalled by the Japanese automaker. The NHTSA confirmed that Toyota did not provide black box data recorders on most of its vehicles until after 2007. Complaints of unexpected acceleration began in 2000. Plaintiffs' experts also contend that data is not even recorded in slow-speed collisions where an air bag is not deployed.

Although NHTSA testing has not revealed any defects other than pedal entrapment and sticking gas pedals, its investigation is continuing. A final report, with input from NASA and the National Academy of Sciences, is expected next year. Research is presently under way to determine whether electromagnetic interference could have contributed to the acceleration problems.

The recent NHTSA findings do not definitively establish the cause of acceleration, due to the relatively small amount of Toyota vehicles equipped with black boxes. Defense attorneys, however, may try to use the findings to support arguments that the acceleration was caused by operator error.