“Even among the highest-risk inflaters, ruptures are not common,” Mr. Rosekind said at the recent meeting. “But as we’ve said, even these low odds of rupture are unacceptably high. And some consumers may prefer not to drive their vehicle until it is fixed.”

Dr. David Lilienfeld, a physician from Foster City, Calif., found himself in this predicament. He said he and his wife had owned about half a dozen Hondas over the years and rarely gave competing brands a second look. But after waiting nearly five months for the airbag in his 2004 Honda Civic to be fixed, his loyalty began to waver.

Dr. Lilienfeld, 58, called two dealerships in July, which took down his contact information and told him he could be waiting awhile. Months passed. “This is absurd to have to wait five months for something that is potentially deadly to be repaired,” he said.

That finally changed last week, when he escalated his complaint by calling Jeffrey Conrad, senior vice president and general manager of Honda. The next day, his car was picked up and towed into the Honda service bay.

“At least my faith in the company has been restored, though I don’t think it should have required my talking with a V.P. to do it,” he added.

By contrast, Libbie Nofzinger, a 25-year-old student from Toledo, Ohio, had a more seamless experience. When she took her 2004 Honda Accord to the dealer for an oil change last month, workers noticed that it had been recalled and provided her with a rental car while it was repaired. “It was pretty easy,” she said. “I got my car back the next morning.”

Millions of additional vehicles with Takata’s ammonium nitrate inflaters are still on the road and will be recalled at the end of 2018 unless new information surfaces establishing that they are safe. Another category of Takata inflaters now uses a desiccant, a chemical that helps combat the effects of moisture, in an attempt to make ruptures less likely. But regulators said even those would be recalled unless Takata can demonstrate their long-term safety by the end of 2019.