G.M. Unit’s Self-Driving Taxis Are Subject of U.S. Safety Investigation

The agency, the National Highway Traffic Safety Administration, said in a filing posted on its website that it had received reports that autonomous taxis operated by G.M.’s Cruise division had become immobilized on roadways, creating obstacles for other vehicles. The agency also said G.M. reported three incidents in which Cruise vehicles slowed suddenly and were hit from behind.

The agency said its Office of Defects Investigation would try to determine the scope and severity of the two types of incidents.

Regulators are increasingly scrutinizing autonomous and semiautonomous cars, and the claims automakers have made about them. The auto safety agency’s most high profile investigation in this area involves Tesla’s self-driving technology. Regulators are looking into at least 14 crashes involving Tesla cars driving on Autopilot that resulted in 19 deaths.