At least 74 people have died in General Motors cars in accidents with some key similarities to those that GM has linked to 13 deaths involving defective ignition switches, a Reuters analysis of government fatal-crash data determined.

Such accidents also occurred at a higher rate in the GM cars than in top competitors’ models, the news agency's analysis showed.

Reuters said it had searched the Fatality Analysis Reporting System (FARS), a national database of crash information submitted by local law-enforcement agencies, for single car frontal collisions where no front air bags deployed and the driver or front seat passenger was killed.

The news agency compared the incidence of this kind of deadly accident in the Chevrolet Cobalt and the Saturn Ion, the highest-profile cars in GM's recall of 2.6m cars with defective switches, against the records of three popular small car competitors in the US - the Ford Focus, Honda Civic and Toyota Corolla.

The analysis found that the frequency of such accidents in the Ion was nearly six times that of the Corolla and twice that of the Focus. The Ion had 5.9 such fatal crashes per 100,000 cars sold, followed by the Cobalt (4.10, Focus (2.9), Civic (1.6), and Corolla (1.0).

"It is not clear how many of the deadly accidents identified by Reuters involved defective ignition switches, because crash reports typically do not include that data. That leaves open the possibility that air bags may have failed to deploy in some of the GM crashes for reasons other than faulty switches," the news agency stressed.

GM told Reuters it had derived the tally of 13 deaths from claims and lawsuits filed against it. The automaker checked those claims and lawsuits against other sources available to it, including vehicle data recorders recovered from some crashes.

Reuters' analysis relied on the FARS database, which encompasses a much wider universe of accidents. GM reportedly declined to say whether it had used information from the federal database.

Reuters said it had disclosed its findings in detail to GM and federal regulators at the National Highway Traffic Safety Administration (NHTSA).

GM declined to comment on Reuters’ findings or methodology, responding only: "Our focus is on doing the right thing for customers — fixing the recalled vehicles as quickly as possible, addressing our civic and legal responsibilities and setting a new industry standard for safety."

NHTSA Acting Administrator David Friedman told Reuters: "The final death toll associated with this safety defect is not known to NHTSA, but we believe it’s likely that more than 13 lives were lost."

Ford said it took issue with the Reuters findings concerning the Focus but didn’t specify its reasons.

Using the FARS database of crashes reported to US safety regulators between 2003 and 2012, Reuters identified 45 front-seat fatalities in the Cobalt and 29 in the Ion. In similar crashes, there were 44 fatalities in the Focus, 41 in the Civic and 24 in the Corolla.

Reuters found the Focus had 43 fatal accidents, the Cobalt had 42, the Civic had 39, the Ion had 28 and the Corolla had 24. While the raw crash numbers appear comparable, the rate of deadly crashes was higher in the two GM models, as the Ford, Honda and Toyota models sold in substantially greater numbers.

David Zuby, executive vice president and chief research officer at The Insurance Institute for Highway Safety, a non-profit safety research group connected with the US insurance industry, reviewed the Reuters analysis and said: "Your crash rates suggest that Cobalt and Ion are less crashworthy than the other models for which you’ve computed similar statistics," and are similar to those in a 2011 IIHS analysis.

Zuby said there were several limitations to the analysis, noting that "while [Reuters] analysis does focus on circumstances that are similar to the cases involving GM air bags that failed to deploy because of the ignition switch problem, it cannot be said definitively that the ignition switch problem" caused 74 deaths.

It is possible, Zuby added, that limitations in the data examined by Reuters may overstate the number of deaths attributable to air bag non-deployment in the car models examined.

GM files 2,004 ignition switch-related injury/death reports

Full GM recall coverage to date here