Company does not recall half the cars with switch it told dealers might fail and stall car.
General Motors' recall of the Chevy Cobalt and Pontiac G5 covers fewer than half the GM cars on U.S. roads that it years ago told dealers might have the ignition switch problem linked to at least six deaths.
The car company continues to decline to explain publicly why it believes some vehicles with the apparently identical ignition switches are at risk for shutting off unexpectedly and others are not.
GM says it based the Feb. 13 U.S. recall of 619,122 of its 2005 to 2007 Chevrolet Cobalt and 2007 Pontiac G5 compacts on its investigation of the problem. It says it doesn't rule out a wider recall, and talks with the National Highway Traffic Safety Administration officials continue.
But another 658,172 vehicles of other models are on the road that were identified by GM as early as 2005 in a dealer alert as having the same potential switch problem. The vehicle tally is from an analysis of Polk vehicle registration data for USA TODAY by TrueCar.com.
Not recalled, but identified by GM in dealer service bulletins along with the recalled cars, are the 2006 and 2007 Chevrolet HHR and Pontiac Solstice, the 2003 to 2007 Saturn Ion and the 2007 Saturn Sky. They all use switches with the same part number, an automaker's definitive way to identify components, as the recalled cars.
In announcing the recall, GM said that jarring or heavy key chains could cause switches to move out of the "on" position, shutting off the engine and power systems — and disabling air bags, which is the key safety issue in the recall. The company said it knew of 22 crashes, including five in which airbags did not deploy and six people were killed.
Asked why jarring or heavy key chains would not lead to the lead same problems with the switch in the non-recalled vehicles, GM spokesman Alan Adler told USA TODAY in an e-mail, "GM has devoted significant time and resources to evaluating this issue, and has concluded that the 2005-2007 Chevrolet Cobalt and the 2007 G5 should be recalled ... given our present understanding of the 2005-2007 Cobalt and 2007 Pontiac G5 ignition" switch issue.
But there have been similar complaints made about the non-recalled models.
Two HHR owners complained to NHTSA about air bags not deploying in front-impact crashes.
A May 2009 report by TV station WTVD in Raleigh, N.C., quoted Loretta Barnes as saying her 2007 HHR "stalled on the train track" in Roanoke Rapids. She said she was able to quickly restart the vehicle but that it was a recurring problem, and "I'm scared."
She said she had taken her HHR to the dealership five times without the problem being solved. As a result of the TV report, Barnes said, GM gave her a deal on a new car.
Contributing: USA TODAY's Paul Overberg