NHTSA Complaint #11450430 — 2018 TESLA MODEL 3

I drive twice a week from Washington DC to Charlottesville, VA, a distance of 117 miles each way. 35 miles are on an interstate and 82 miles are on a divided 4-lane state road. Since I restarted this commute in September 2021 after Covid shutdowns and summer break, I have experienced recurring, frequent problems with the car's vehicle warning system, adaptive cruise control, and forward collision notification system. When I drive on the interstate (where there is currently a great deal of construction), the adaptive cruise control keeps automatically adjusting my speed when there is no speed limit change. So I might be traveling at 65 mph when my speed is suddenly lowered to 30 mph. There are no warnings, either visual or audio. The speed just changes. This is incredibly dangerous and requires me to be hyper-vigilant to avoid a rear end collision, or to turn off the cruise control system. When I travel on the state road, I receive frequent visual notifications of a collision risk ahead of me. I received four of them yesterday, and there was nothing in front of me at all. But sometimes, all automated systems disengage, a visual warning appears on my vehicle screen, and a loud klaxon sounds. This happened twice yesterday. It often occurs when I'm driving on a hilly stretch of road, when I'm ascending towards a crest in the roadway. It happens more at night than in daylight, but it happens without warning under a variety of conditions. The car also has an automatic lane change feature, which used to work reliably, but now seems more capricious, for no apparent reason. I engage the system, the screen shows it's safe to change lanes, the vehicle initiates the lane change, and then the car suddenly lurches back into the lane I'm leaving, saying the function isn't available. This has happened in all traffic conditions, from an empty highway to one with moderate traffic. I don't use the system when there's a lot of traffic.