The News reports that the NHTSA probe comes on the heels of a single complaint, citing "inappropriate activation of the emergency braking system." The official complaint states that the driver "alleges that the driver assist system inappropriately activated emergency braking bringing the vehicle to a complete stop under what the driver considered to be full braking force."
NHTSA reports that the driver "heard three to four beeps from the forward collision avoidance system" in the vehicle in question (a rental 2014 Impala with just 2,500 miles on the odometer), and that "this was immediately followed by an autonomous brake activation resulting in their vehicle being struck from the rear by another vehicle." No police report was filed following this incident, and there were no injuries.
A General Motors spokesperson told The Detroit News that the company is fully cooperating with this preliminary investigation. Stay tuned for more information as it becomes available.