WASHINGTON—Consumer advocates and safety groups have raised concerns that flawed electronics could be causing unwanted acceleration in the Toyotas. They have questioned the reliability of the event data recorders studied by the government, saying they could be faulty or fail to tell the whole story of the individual crashes.
Joan Claybrook, a former NHTSA administrator who previously led consumer group Public Citizen, said the government investigation discounted research conducted by plaintiffs' attorneys.
"The facts are still quite substantial that there's a problem and I think they could have done a lot more in terms of gathering more expertise," Claybrook said.
To promote safety, LaHood said NHTSA was considering new regulations. They include requiring brake override systems on all vehicles, standardizing keyless ignition systems and requiring event data recorders, or vehicle black boxes, on all new vehicles.
Transportation officials said they would also consider conducting more research on electronic control systems and review the placement and design of accelerator and brake pedals.
Since the recalls, Toyota has installed brake override systems on new vehicles. The systems automatically cut the throttle when the brake and gas pedals are applied at the same time.
The company also created engineering teams to examine vehicles that are the subject of consumer complaints and appointed a chief quality officer for North America amid complaints its U.S. division did not play a large enough role in making safety decisions.
Toyota's safety issues received broad attention from the government after four people were killed in a high-speed crash involving a Lexus near San Diego in August 2009.
NHTSA has received about 3,000 reports of sudden acceleration incidents involving Toyota vehicles during the past decade, including allegations of 93 deaths. NHTSA has confirmed five of them.
Congress considered sweeping safety legislation last year that would have required brake override systems, raised penalties on auto companies that evade safety recalls and given the government the power to quickly recall vehicles. But the bills failed to win enough support.
The National Academy of Sciences is conducting a separate study of unintended acceleration in cars and trucks across the auto industry. The panel is expected to release its findings this fall.