NHTSA Complaint #11451848 — 2021 TESLA MODEL Y

When using the cruise control (and, by extension, Autopilot) feature, the car often brakes unexpectedly and in some cases dramatically for no obvious reason. I often use cruise control on single lane undivided roads that have speed limits between 35-50mph. When using cruise control in this scenarios the car will often automatically apply the brakes for no obvious reason, often applying the brakes hard enough that the car slows down quickly. Many times the forward collision warning sound is played but there is nothing in front of me in my lane or in the opposite lane. Other times this happens when a car is approaching me in the opposite lane. There have been several cases where the car applied the brakes for no obvious reason so hard that had I not intervened (by pressing the accelerator) the car behind me would have been at risk of hitting me. It has gotten to the point where I am becoming somewhat conditioned to override the automatic braking anytime it happens. That is dangerous and can lead to an issue where the car legitimately has a reason to decelerate but I override it thinking it is braking for no reason. I see this behavior in both cruise control (which Tesla calls Traffic Aware Cruise Control) or in Autopilot. I don't currently have the Full Self Driving feature of the car. It occurs most often when I'm on a single lane undivided road using either cruise control or Autopilot. When I'm using cruise control or Autopilot on a traditional divided highway the unexpected braking happens much less frequently.