NHTSA Complaint #11479657 — 2021 TESLA MODEL Y

Reporting numerous instances of ghost braking while Adaptive Cruise Control is enabled. These are instances of sudden deceleration of the car when no other vehicles or obstructions present while traveling on 4 lane highways at freeway speeds. Requires overriding ACC feature by engaging the accelerator to maintain speed and avoid a possible rear end collision. Rear end collision is the most of the highest risk when this sudden deceleration occurs. No warnings were given before the deceleration. These episodes are most noticeable when traveling at freeway speeds of 65+ mph in open terrain with no curves. One instance could be attributed to a shadow across the roadway, however, more times than not shadows across the roadway didn't cause ghost braking. The point being that there often is no rhyme or reason that can be identified or repeated. This problem is a known problem that Tesla is aware of as well as the NHSTA.