2020 MAZDA MAZDA3 Forward Collision Avoidance Adaptive Cruise Control Problems

The Mazda Radar Cruise Control (MRCC) system performs poorly (it does not hold a set speed well up and down hill; compared to our 2006 Mazda3), but the safety concern is the forceful, sudden, and not-always-predictable braking the vehicle does even if there is not another vehicle in front of us. It brakes, sometimes, for a vehicle in the right lane (we, in the left), and continues to brake unless we override the system. No problem--except if there may be someone following too closely, it could cause a collision. It seems to be related to the MRCC, as no "Brake!" warning accompanies the unwanted brake application. I've contacted Mazda numerous times; they recommended taking it to the dealer. I have--they can find nothing wrong. All of this seems related to a MRCC update (SSP C5) that was done to smooth the MRCC's operation. It did fix the sudden deceleration and...

The front radar sensor failed and doesn’t work anymore rendering the FCW and ACC useless. There is a TSB out about water damage getting into the sensor. There are 2 warning lights on. They first appeared when I turned on my car one day.