While driving, the car did an automatic hard brake for no reason. Traffic was accelerating after being stopped at a red light. The car in front of me was not braking and was accelerating away from me when suddenly the car hard brakes with no warning beforehand. It braked hard enough to throw me forward and cause traffic behind me to have to hard brake in order to keep from rear-ending me. There was an on ramp coming in near me but again that traffic was not in my lane. I have not complained to the dealership yet so it has not been reviewed and I have no reports since an accident did not happen. There were no warning lamps or messages before the event; although the brake light came on when the hard brake occurred, but not before. This was the first time it has occurred since purchasing the car about a year and a half ago. It was terrifying. It’s an hour later and I’m still shook up.