Did feds delay public disclosure of Chevy Volt fire risk to protect GM sales?

The National Highway Traffic Safety Administration crashed a Chevrolet Volt back in May, the car's lithium-ion battery burst into flames in June, and the agency acknowledged the fire to the public and launched a safety investigation in late November. Why the six-month time-lapse?

Joan Claybrook, a consumer advocate who ran the NHTSA from 1977 to 1981 has an answer. She told Automotive News the delay was "because of the fragility of [Volt] sales."

That's a strong accusation. In six words, she implied that the NHTSA held off on its public report to protect its sister agency General Motors (oh, I'm kidding) from any hit the Volt might take to its already creaky sales. (This past October, before the fire was made public, Jalopnik wondered whether the Volt was a bona fide sales flop.)

Yes, she raises a compelling question. Claybrook is a longtime consumer advocate who once helmed the advocacy group Public Citizen — the one Ralph Nader founded in 1971 — and whose legacy includes working with Nader to get the first major piece of automotive-safety legislation passed.

Only trouble is, she offers no proof that the NHTSA's delay was engineered to help GM. Just a plausible scenario.

You may recall that Claybrook also jumped into the last high-profile question of automotive safety. In 2010, she slammed Toyota on ABC's Good Morning America, accusing the company of stonewalling an investigation into cases of unintended acceleration. Again, plausible but no proof.

Some have pointed to the NHTSA's odd, politically-charged statement on the Volt fire as evidence the agency cut GM's Volt program six months of slack.

NHTSA continues to believe that electric vehicles have incredible potential to save consumers money at the pump, help protect the environment, create jobs, and strengthen national security by reducing our dependence on oil. In fact, NHTSA testing on electric vehicles to date has not raised safety concerns about vehicles other than the Chevy Volt.

A controversial stance to some, yes, but no proof of collusion.

What we do know is back in May, the NHTSA performed a side-impact crash test on the Volt. The crash damaged the car's battery and ruptured its coolant line. Three weeks later, while parked in an NHTSA facility, the Volt caught fire. A GM spokesman told Automotive News that the company began investigating the fire in June.

GM engineers were unable to replicate the fire until November, when a battery finally caught fire in a GM testing facility after a simulated side-impact test. GM has developed a procedure that will allow towing companies and repair shops to drain the Volt's battery after an accident.

Since the fire became public knowledge last month, GM began offering free loaner cars to Volt owners who are worried about the car's safety. Automotive News says 33 people have taken GM up on the offer.

So why did the NHTSA wait so long before going public with the story of the fire and its aftermath? Perhaps it's merely this: Until GM could replicate the problem, which didn't happen until November, the agency had no basis on which to determine its potential impact on safety.

Or should the NHTSA have fired off the same half-cocked, knee-jerk response as a "consumer advocate"?