NHTSA Complaint #11454561 — 2017 TESLA MODEL S

Additional report for same problem with DIFFERENT car. This report is not about a single incident, but rather a REPEATED problem over several years with the adaptive cruise control on 3 different Tesla cars I have owned. These cars are a 2017 Tesla S, and 2 different 2021 Tesla Y models. in each case, whenever these cars are driven on a highway with the adaptive cruise control engaged, several times during each hour of driving, the cars will rapidly brake/decelerate with no action taken to cause the situation by the driver, nor any external situations with the traffic that would justify them. With the Tesla regenerative braking, these deceleration events are so extreme that it would be easy to imagine an accident with a car following closely behind. Indeed, with these situations occurring with no warning and extreme braking they are quite frightening to the passengers traveling in the car. During the most recent occurrence, I noted the exact day and minute of it's occurrence, and filed a service request with the local Tesla office. Even with the exact time of this event, the service center was unable to find anything wrong with the car. The Tesla service center attributed this issue to problems with the Autopilot and Full Self Driving software, but none of my cars have had this optional software-only the software which came standard on each of these cars. While otherwise appreciating the good characteristics of these cars, this unexplainable deceleration problem is what caused me to sell the prior 2 models before purchasing this latest model Y, hoping that this problem would not recur. It is worth noting that I have owned several other make and model cars with comparable adaptive cruise control, yet this situation never occurred even once on any of these other makes of cars.