The US National Highway Traffic Safety Administration (NHTSA) is investigating comma.ai’s aftermarket driver-assistance technology after identifying five crashes involving cars that struck slow-moving or stopped vehicles. The crashes caused three deaths and injured 11 people, raising concerns about whether the systems can reliably detect hazards and safely augment vehicles’ own driver-assistance features.

Comma.ai’s openpilot software and Comma Four device provide functions including lane centring and adaptive cruise control across more than 325 car models from 27 brands. More than 30,000 drivers have reportedly used the system over 402 million miles, but at least two investigated crashes involved collisions with stationary vehicles, including a first responder’s vehicle, while another involved a merging vehicle. NHTSA is also examining which software versions were installed, as at least two crashes involved modified versions, including the fatal crash’s use of FrogPilot.