These types of bulletins are sent out to dealer service departments as an advisory about known problems that don't rise to the recall level. Typically, owners aren't told about such issues but will find themselves getting repairs at no charge if they complain.
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But things have changed.
"The entire industry is under the microscope," said David Sullivan, senior auto analyst with consulting firm AutoPacific. Carmakers "aren't going to sit on anything anymore," he said.
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In GM's case, industry observers suggest that the maker is doing a rapid clear-out of safety-related problems that it had hadn't yet decided to act upon. That's in line with what happened with Toyota after its problems with so-called unintended acceleration were first reported in 2009. The Japanese automaker also became far more aggressive about safety issues—a major reason why it has had the most vehicles of any manufacturer covered by recalls in the U.S. for five of the last six years.
After hitting the previous record of about 31 million vehicles in 2004, the numbers declined for several years, according to NHTSA data. But they've been on the rise since the Toyota scandal erupted. Last year, the number of U.S. recalls reached about 22 million, according to NHTSA, a figure that the industry could top before mid-year if it stays on its current course.
"There's a good chance of a new record" for recalls this year, Ditlow said.
—By CNBC contributor Paul Eisenstein.
CNBC's "Failure to Recall: Investigating GM" will premiere Sunday, May 18 at 10 p.m. ET/PT.