Auto-safety regulations in the United States launched an investigation into whether Mercedes-Benz has been too slow to disclose safety recalls and defects as well as to make repairs.  The National Highway Traffic Safety Administration sent a letter to the top executives asking them to explain delays in notifying owners about safety defects and how they’re carrying out recalls.

The letter claimed communications with regulators were missing details about repairs.  Mercedes also did not provide enough data so that consumers could check for open recalls on the NHTSA website.

“Repeated and lengthy disruptions of MBUSA’s service result in the motoring public not being able to access safety critical information about their MBUSA vehicles and/or confusion over whether a safety recall applies to their vehicle,” NHTSA’s Stephen Ridella wrote to R. Thomas Brunner, the senior manager of regulatory and government compliance at Mercedes-Benz USA.

The NHTSA’s letter says the agency notified Mercedes in May that it failed to tell vehicle owners within the required 60 day time period about recalls affecting their vehicles.

“The safety of our customers is our highest priority,” Mercedes-Benz spokesman Robert Moran said in an email responding to the claims. “We make every effort to ensure our recall campaigns and customer notifications are executed in a timely manner. We will work closely with NHTSA on this audit query to address its concerns.”

The agency is asking Mercedes to provide information about how it handled over 24 recalls in the past three years.  In 2015, NHTSA fined Fiat Chrysler over $105 million in penalties, and Honda was fined over $70 million.