Last autumn, the National Highway Traffic Safety Administration(NHTSA) launched a probe into Tesla's Autopilot software.
The problem under investigation is how Tesla's driver-assistance software detects potential incidents with stopped first responder vehicles.
Also how the cars notify drivers of these issues.
The NHTSA has investigated 16 crashes so far.
They discovered that Autopilot aborted its own vehicle control "less than one second prior to the first impact" on average.
However, video of these events show that the driver could have been made aware on average eight seconds before impact.
A total of 830,000 Tesla vehicles are part of the investigation, including Model S, Model X, Model 3 and Model Y.
