After starting from a stop after the traffic light turned green, the car in front of me pulled ahead as they accelerated faster than me. When the car in front of me was about 50 yards in front of me, and I had reached about 25 miles per hour the car's collision avoidance system engaged and slammed on the brakes and brought me to a full stop. The car in front of me had not applied their brakes or slowed at all, and there were no visible obstacles. My car stopped so suddenly that I thought I had been hit from the rear at high speed until the red warning lights appeared on the dash (after the braking started). The cars behind me almost ran into me because of the sudden stop.

- Upland, CA, USA