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DETROIT (CBSMiami/AP) — U.S. safety regulators have launched an investigation into automaker BMW over it’s Mini brand.

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The National Highway Traffic Safety Administration says it’s investigating the company’s Mini brand because it may have been slow to fix cars that didn’t pass federal crash tests.

At issue are just over 30,000 Mini Cooper and Cooper S models from model years 2014 and 2015, plus the John Cooper Works from 2015.

The agency said in paperwork posted on its website Monday that government crash tests found that a 2014 Mini Two-Door Hardtop Cooper didn’t adequately protect a female dummy in side-impact crash tests done in October of last year. Two months later, BMW agreed to a recall and later said it would do a “service campaign” to add padding to the rear side panels of 2015 Two-Door Hardtop Cooper models.

But the campaign was never done, and BMW never told NHTSA that it wasn’t, according to the documents.

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Then, in July 2015, NHTSA tested a 2015 Cooper S, which also failed the side impact crash tests, and BMW agreed to recall the 2014 and 2015 Cooper S and Two-Door Hardtop and 2015 John Cooper Works models.

The agency said it’s concerned that BMW knew or should have known about side crash problems and should have taken action sooner. “It appears from a review of NHTSA’s databases that BMW may have failed to submit recall communications to NHTSA in a timely manner,” the documents said.

Messages were left Monday seeking comment from Mini and BMW spokesmen.

NHTSA has the authority to fine an automaker up to $35 million for failing to act quickly on safety problems or failing to communicate with the agency. Since the start of 2013, Fiat Chrysler, General Motors, Honda, Hyundai, Ford, Toyota and air bag maker Takata all have been fined by the agency.

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