Based on news reports, lawsuits, police and fire records, and research by advocacy groups, at least 36 people have been killed in the United States in such incidents since 2006, including seven in the past six months. Dozens of others have been injured, some left with brain damage.
The deaths of Ms. Penney and Mr. Livingston were all the more striking because of their accomplishments in academia and science. Before retiring to Florida, Ms. Penney was the first woman to serve permanently as chancellor of the University of Massachusetts Boston and held other leadership roles in the UMass and State University of New York systems. Mr. Livingston, an expert on magnets, spent decades as a researcher at General Electric and taught at the Massachusetts Institute of Technology. The couple collaborated on a book about Martha Wright, a women’s rights figure in the 1800s who was Mr. Livingston’s great-great-grandmother.
“These are very smart people,” Ms. Livingston said. “This kind of situation can happen to anybody.”
The National Highway Traffic Safety Administration, which oversees the auto industry, proposed a rule for keyless vehicles in 2011 mandating a one-second audible external warning to drivers to turn off the ignition. The rule would cost the auto industry $500,000 a year, according to an agency estimate. But after lobbying from the industry, the proposal has remained in limbo.
Asked recently for comment, the agency repeated earlier guidance, pointing consumers to a safety video about the use and potential dangers of keyless ignitions.
Some keyless models activate audible warnings or flashing lights inside or outside the car if the door is opened while the motor is running. The Toyota Avalon, for example, is designed to beep once internally and three times externally in such circumstances. But as the deaths of Ms. Penney and Mr. Livingston indicate, such alerts are not always adequate.
“I think if they bought a different car, they’d be alive,” Ms. Livingston said.
Contacted for this article, the automaker said, “Toyota vehicles meet or exceed all regulatory safety standards.”
An investigation by The New York Times last year highlighted the extent of the hazard with keyless ignitions and the regulatory inaction. Soon after, Senator Richard Blumenthal, a Connecticut Democrat, demanded during a hearing that the highway safety agency adopt its proposed rule and require carmakers to make vehicles shut off automatically after a set period of idling. Earlier this year, Mr. Blumenthal introduced a bill to do just that.
The Senate legislation, the Park It Act, has yet to be scheduled for a committee hearing. But this month a group of House members — three Democrats and a Republican — introduced an identical bill in the Energy and Commerce Committee.
“This is something we clearly have the technology to prevent,” Representative Jan Schakowsky, an Illinois Democrat and the bill’s lead House sponsor, said of the carbon-monoxide deaths.
Ford and General Motors have announced their support for the legislation.
Some automakers have added an automatic shut-off, including Ford on all its keyless vehicles since the 2015 model year. G.M. retrofitted some of its vehicles to add the automatic shut-off, at $5 apiece, the company told regulators.
Toyota, whose vehicles have been involved in half of the fatal incidents, has announced that its 2020 keyless models will come with an automatic shut-off function. It would not say whether it supported the congressional legislation.
Hyundai said that it backed the legislation and that it planned to install the auto-shut-off technology in new models, but did not offer a timeline for doing so.
A representative of Fiat Chrysler said the company was reviewing the legislation, but added that “statistics show no increase in such injuries when compared with vehicles featuring conventional rotary-key ignition systems,” and that “automatic shut-off technology may have unintended consequences.”
Nissan, Daimler, Mazda and Subaru declined to say whether they had a position on the legislation. Several automakers did not respond to inquiries.
While mandated safety features remain elusive, millions of cars with keyless ignitions are on the road. The feature is now standard in more than half of the vehicles made each year, according to the auto information website Edmunds.
“Those cars might be out there seven, eight, 10 years,” Ms. Livingston said. “What about all those other people that might die?”