NHTSA complaint #11543938

Owner complaint summary

On 9/3/23 we were traveling from Moab UT to Green River UT and the cruise control was engaged at highway speeds. We were not using the "Autopilot" functionality. Without warning, the car suddenly decelerated under what felt like hard braking. There was no warning immediately before the hard braking started and the car had no warning indicators of any kind either before or after the incidents. The hard deceleration happened at least four times. One of those times a raven flew up from the road, but the other times there was nothing in the road. At least three of the incidents occurred on highway 6 traveling north. The last time it occurred was on I-70 westbound after we stopped the cars and cleaned all the cameras and ensured there was no debris on the front bumper which could cause issues with the forward-looking radar. We lost confidence in the cruise control feature and did not enable it for the rest of the trip. This is a safety issue because the car does not just reduce speed, it feels like it is braking hard or perhaps full regeneration of the battery. Either way, on these 2-lane highways, there are often situations when other drivers are driving too close to the rear bumper and a sudden, inexplicable hard braking is very likely to cause collision. A collision at these speeds could push the car into oncoming traffic, leading to fatalities. We asked Tesla service to look into the issue, and said there is likely footage of at least one of the events (because I honked the horn to start recording). The Tesla service person gave several reasons why it deceleration may occur, but Tesla is neither reviewing the footage, nor taking action to remedy the issue. They said "Our remote diagnostics has confirmed the vehicle hardware is operating as expected and there are no repairs the service team can make in regards to this." With service unable to make a fix to the car, this problem remains unresolved and we have lost confidence in cruise control.