Drivers using Tesla Autopilot were involved in hundreds of crashes in just 10 months

• The US government released long-awaited data on car crashes involving driver-assistance systems.
• Teslas on Autopilot accounted for 273 of the 392 crashes reported since last July.

Vehicles using Tesla's Autopilot software were involved in 273 crashes over roughly the last year, according to a report released Wednesday by the US road-safety regulator.

The report from the National Highway Traffic Safety Administration offers the clearest picture yet of how bleeding-edge advanced driver-assistance systems (ADAS) from Tesla and others perform on US roads. ADAS features can automate vehicle functions like steering, braking, and acceleration but stop short of making a car fully autonomous.

The data comes from an order NHTSA gave to automakers last June instructing them to report any known incidents involving their driver-assistance technologies, known as Level 2 systems. Regulators also told autonomous-vehicle companies like Waymo to share information about crashes as they occur.

Automakers reported 392 crashes involving their ADAS systems in total between July of last year and May 15, with Tesla logging by far the most. Honda was next with 90 crashes. Subaru had 10, Ford had five, and Toyota had four. Seven other carmakers reported three or fewer incidents.

Some of the reported incidents involved other vehicles colliding with an automaker's ADAS-enabled cars.

The research is part of a broader effort by the US government to understand the risks and safety benefits of ADAS features, which are becoming increasingly common and which encourage drivers to yield an increasing array of driving tasks to their vehicles, from parking to changing lanes.

Tesla in particular is under intense scrutiny from regulators after a string of crashes in which Autopilot-enabled cars crashed into stopped emergency vehicles. Although Tesla tells drivers they need to pay full attention, safety experts have criticized Autopilot for encouraging distracted driving. Numerous videos have popped up over the years depicting drivers sleeping or otherwise abusing Tesla's system.

Without information about how many ADAS-equipped vehicles each manufacturer has on the road and the number of miles they travel, it's impossible to say whether one system crashes more frequently than another.

Every vehicle Tesla sells comes with Autopilot, which enables a car to automatically follow lane lines and maintain a set distance to the car ahead. Other manufacturers typically offer their comparable features as options, which may skew the data in their favor.

NHTSA also warned that some manufacturers can access crash data more readily, which may impact the data. Some crashes may have gone unreported, while others may have been counted twice if they involved multiple vehicles running ADAS systems, NHTSA said.

In a statement to Insider, Honda said the public shouldn't draw "apple-to-apple comparisons" between automakers, since they have different methods of gathering crash data and varying fleet sizes.

Self-driving vehicles were involved in 130 incidents, NHTSA said in a separate report. Waymo, the Google-owned startup that is experimenting with driverless taxis, reported the most: 62 incidents.

A Waymo spokesperson said: "We see value in having nationally standardized and uniform crash reporting during this early stage of the development and deployment of autonomous driving technology, and there's public benefit in NHTSA sharing its findings. We also believe any reporting requirements should be harmonized across all U.S. jurisdictions to limit confusion and potentially enable more meaningful comparisons, and NHTSA's effort is a step toward achieving that goal."