2020 Mazda MAZDA3

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 acceleration when following other vehicles, but now is worse in other aspects. I may be wrong, but it all seems to be a software issue, so it's not surprising that the dealer can find "no concerns". As to the date of this incident, it happens nearly every time we take the car on a highway or interstate.

I was driving 35MPH on a side street in “sport” mode. Car system beeped, car auto stopped, red circle with explanation mark and the word Break appeared on my center console. My drive shift popped out of Drive. No object was in front of my car, nothing ran out in front of it. Fortunately, there weren’t any other cars behind me or an accident would have followed.

THIS CAR IS ONLY A FEW MONTHS OLD, WITH ONLY 1600 MILES. WHILE DRIVING AT APPROX 30 OR 40 MPH THE SMART BRAKE SYSTEM (SBS) FALSELY DETECTS RANDOMLY AN OBSTACLE WHILE DRIVING, ACTIVATING THE AUTOMATIC EMERGENCY WARNING LIGHT AND ALARM. THE MAZDA DEALER WAS UNABLE TO DUPLICATE OR REPAIR THE PROBLEM ALTHOUGH THIS HAS BEEN REPORTED NUMEROUS TIMES AND WAS PART OF AN EARLIER RECALL. I.E.MAZDA RECALL NUMBER 4219L

I WAS DRIVING MY VEHICLE STRAIGHT AHEAD ON A TWO-WAY CITY STREET WITH NO OTHER VEHICLES IN FRONT OR ON MY SIDES. I WAS TRAVELING AT A SPEED OF 40 MPH. THE TWO-WAY STREET IS SEPARATED BY A CONCRETE DIVIDER AND TROLLY TRACKS. A "BRAKE!" ALERT APPEARED ON THE DISPLAY SCREEN FOLLOWED BY BEEPS. SUDDENLY THE BRAKES WERE ENGAGED BRINGING THE VEHICLE TO A COMPLETE STOP CAUSING THE VEHICLE BEHIND TO COME TO A SCREECHING HALT. IN A FEW SECONDS I WAS ABLE TO DRIVE OFF.