companies, consumers, automotive reviewers and even its own dealers and mechanics about abnormal crashes that have since been linked to a faulty ignition switch.
The files show many missed opportunities to ask questions and connect disparate events—the very type of evidence that is supposed to be routed to and vetted by the government's Early Warning Reporting system for potential automotive defects.
There's no indication in the files whether GM did or didn't follow through with the vehicle inspection requested by Vanguard in the Barstow, Calif., incident. GM did tell NHTSA that there may not be sufficient information to assign cause to the crash. Enterprise in 2007 bought Vanguard's Alamo and National brands.
Alan Adler, a company spokesman, declined to discuss specific cases for this story. He said the auto maker has modified how it handles product defect questions raised by rental-car companies and other fleet customers.
GM's decision to change some of its safety-monitoring practices came after it had to order recalls early this year for the Cobalt, Ion and four other U.S. models for a flaw that had been kept from the public for at least a decade. The auto maker has said that those cars—about 2.6 million of them—may have had faulty ignition switches that when bumped could shut off engines while driving and disable air bags.
By the end of June, the number of cars in North America that GM had called back for repairs related to the ignitions had passed 16 million, more than the 9.71 million vehicles the company sold worldwide in 2013.
The role of rental cars in the GM ignition-switch controversy has not yet been fully examined.
Rental cars tend to be driven a lot of miles. They're used by different drivers all the time, many of whom are unfamiliar with the vehicle. That can be the difference in surviving and perishing in an emergency situation, said Clarence Ditlow, executive director of the Washington-based research group Center for Auto Safety.
“The Cobalt was a popular, cheap model for rental-car companies,” Mr. Ditlow said. “This highlights why they should be vigilant about handling recalls.”
U.S. Sen. Barbara Boxer, D-Calif., raised the issue of rental-car repairs with GM CEO Mary Barra during a July 17 hearing on the ignition-switch recall.
GM now backs legislation sponsored by Sen. Boxer and Sen. Charles Schumer, D-N.Y., that would prohibit rental-car companies from renting or selling vehicles subject to a recall that haven't been repaired.
The flaw in the Cobalt, Ion and four other models has been shown to result in stalling, sudden loss of braking and steering and disabling of the air bags.
A woman and her ex-husband were killed in a March 2005 crash in Bee Cave, Texas, after she lost control of a Saturn Ion on a rural road. Their teenage daughter, riding in the back seat, suffered serious injuries including brain damage. A police officer on the scene attributed the crash to a braking and steering defect.
The car's owner, Enterprise, noting potential lawsuits, asked GM for an investigation, including an inspection of the car, according to a Saturn customer-assistance center summary.
A July 2005 letter, two months after the initial back-and-forth between Enterprise and GM, shows Enterprise's contractor ELCO telling GM it had the vehicle inspected and didn't find a defect or malfunction.
In a January 2006 crash in Bucks County, Pa., the police report indicated airbags didn't deploy after a 2006 Cobalt rented from Enterprise slipped off the road and hit a tree, killing the driver.
There was an extended effort to gather information about the crashes, including from the rental companies and the broader consumer fleets. None of the inquiries from NHTSA or the responses from GM gave the agency enough evidence to open a formal defect investigation, a step that could have prompted regulators to order a recall.
The records show that GM's customer service unit referred the case to an investigations unit. There are no records included that show what happened after that.
As part of changes implemented following the ignition- switch recall that started in February, a claim that may involve a potential safety issue is now taken to the newly established Emerging Issues team under GM's global safety division, GM's Mr. Adler said in an email.
The auto maker has reorganized its engineering department in an effort to speed up the handling of potential safety risks and made changes to the legal department in an effort to make sure issues are better communicated than in the past.