By David Shepardson

WASHINGTON (Reuters) -Tesla Inc reported 273 vehicle crashes since July involving advanced driving assistance systems, more than any other automaker, according to data U.S. auto safety regulators released on Wednesday.

Automakers and tech companies reported more than 500 crashes since June 2021, when the National Highway Traffic Safety Administration (NHTSA) issued an order requiring the information.

Car companies are rushing to add driver assistance systems, saying these improve safety by handling some maneuvers. U.S. regulators are trying to understand the practical effect of the changes. But automakers collect and report data in different ways, making it difficult to draw conclusions on systems performance.

Tesla’s advanced driver assistant software dubbed “Full Self Driving” has also created some confusion about vehicle capabilities.

NHTSA ordered companies to quickly report all crashes involving advanced driver assistance systems (ADAS) and vehicles equipped with automated driving systems being tested on public roads.

Of the 392 such crashes reported by a dozen automakers since July, six deaths were reported and five serious injuries. Honda Motor identified 90 crashes.

Companies also reported 130 crashes involving prototype automated driving systems, while 108 involved no injuries and one was a serious injury crash.

NHTSA said Alphabet Inc’s self-driving car unit Waymo reported 62 crashes involving vehicles with automated driving systems, while General Motors’ Cruise had 23.

Waymo said its crashes were not high severity and one third were in manual mode. Airbags deployed in only two crashes.

Cruise said it “has logged millions of miles in one of the most complex urban driving environments because saving lives is our chief aim.”

NHTSA said in releasing the first batch of data that it has already been used to trigger investigations and recalls and helped inform existing defect probes.

“By providing NHTSA with critical and timely safety data this will help our investigators quickly identify potential defect trends,” NHTSA Administrator Steven Cliff said, cautioning the raw number of incidents reported per manufacturer “is by itself inadequate to draw conclusions.”

The agency emphasized crashes are tracked by individual automakers in different ways and discouraged comparisons of performance among automakers in part because there aren’t comprehensive metrics on how widely each system is used.

Tesla did not respond to requests for comment.

Honda told Reuters it had found no defects in the systems and its crash reports were based on unverified customer statements “to comply with NHTSA’s 24-hour reporting deadline.”

No other automaker reported more than 10 ADAS crashes during the period.

Despite the limitations, NHTSA said the data was essential in order to quickly spot potential defects or safety trends. Incidents that occur when an advanced system was engaged within 30 seconds of a crash must be reported within 24 hours to NHTSA.

The agency plans to release new data monthly.

NHTSA has been scrutinizing Autopilot and said last week it was upgrading its probe into 830,000 Tesla vehicles with the system, a required step before it could seek a recall. The regulator had opened a preliminary evaluation to assess the performance of Autopilot after about a dozen crashes in which Tesla vehicles struck stopped emergency vehicles.

Separately, NHTSA has opened 35 special crash investigations involving Tesla vehicles in which ADAS was suspected of being used. A total of 14 crash deaths have been reported in those Tesla investigations, including a May California crash that killed three people.

Tesla says Autopilot allows the vehicles to brake and steer automatically within their lanes but does not make them capable of driving themselves.

(Reporting by David Shepardson; Editing by Muralikumar Anantharaman and David Gregorio)