The National Highway Traffic Safety Administration (NHTSA) has opened a probe into Amazon-owned self-driving technology company Zoox. This follows two separate reports of the vehicles suddenly braking and causing motorcyclists to crash into their rear ends.

The vehicles, Toyota Highlander SUVs equipped with self-driving software, were operating in autonomous mode with a safety driver on board when the incidents occurred. 

The investigation will cover approximately 500 Zoox vehicles and focus on Zoox’s autonomous driving technology.

Analyst QuickTake: This isn't Zoox's first encounter with NHTSA. In March 2023, the agency also investigated the company's assertion that its driverless vehicles met federal safety standards without needing a government exemption.