Republicans sharply questioned the integrity and honesty of the federal auto safety agency Wednesday after it waited nearly six months to notify the public about Chevy Volt batteries catching fire in safety tests.
David Strickland, who heads the National Highway Traffic Safety Administration, said the government "pulled no punches" in its investigation. Amid concerns that the government's partial ownership of General Motors might have tainted its handling of the probe, Strickland said the agency was "transparent" and did its job.
But Republicans challenged the agency chief's claims in a heated hearing on Capitol Hill.
"Well, I hear you. I don't believe you," said Rep. Darrell Issa, R-Calif., chairman of the House Oversight and Government Reform Committee.
Earlier, Issa said the agency "screwed up" by keeping things "secret."
"How dare you not have both the public and this committee know what you knew in a timely fashion," he said.
Strickland said he would have gone public immediately if there were an imminent safety risk. He said it would have been irresponsible to tell people that something was wrong with the Volt while experts looked into the cause of the fire.
The probe began after a test car caught fire in June, three weeks after a side-impact test.
After the first fire, two others occurred later related to separate safety tests, and the agency opened an official investigation on Nov. 25. That ended last week, with the government concluding that the Volt and other electric cars don't pose a greater fire risk than gasoline-powered cars. The agency and General Motors know of no fires in real-world crashes.
The government still owns 26.5 percent of GM's shares.
Ohio Rep. Jim Jordan, who led the hearing by the House Oversight and Government Reform subcommittee, said he found it "deeply troubling" that the agency waited until November to notify the public about the fire.
Republicans questioned whether the delay was to help broker new mileage standards, which were negotiated last year. Strickland insisted there was no connection and said he had not been pressured by anyone from the administration on the investigation.
GM chairman and CEO Daniel F. Akerson said sarcastically that while the company designed the Volt to be a great car, "unfortunately, there is one thing we did not engineer. Although we loaded the Volt with state-of-the-art safety features, we did not engineer the Volt to be a political punching bag. And that, sadly, is what the Volt has become.
"For all of the loose talk about fires, we are here today because tests by regulators resulted in battery fires under lab conditions that no driver would experience in the real world."
Some Democrats came to the administration's defense.
"I don't believe this hearing is about safety," said Rep. Elijah Cummings, D-Md. Instead, he argued, it was part of an attack on the Obama administration's support for GM and the electric car industry.
Rep. Gerry Connolly, D-Va., said Congress should be focused on economic policies that help the recovery and not "political hearings" that undercut U.S. companies.
Jordan argued that the hearing is based on "the facts."
At first, GM blamed NHTSA for the June fire, saying it should have drained the battery to prevent any fires after the test. But the company quickly retreated and said it never told NHTSA to drain the battery. GM executives also said there was no formal procedure in place to drain batteries after crashes involving owners.
Now the company sends out a team to drain the batteries after being notified of a crash by its OnStar safety system.
The Volt has a T-shaped, 400-pound battery pack that can power the car for about 35 miles.
After that, a small gasoline generator kicks in to run the electric motor. The car has a base price of about $40,000.
The Associated Press contributed to this report.