I was slowing down, actively pressing the brake pedal to bring the vehicle to a full stop. As the car decelerated to what my senses and perception registered as a full stop, I pressed the “P” (Park) button while keeping my foot on the brake pedal. I felt the physical click of the “P” button under my thumb while still holding the brake, and my mind registered that the vehicle had successfully transitioned into Park. Before turning around, I visually confirmed that the vehicle had come to a complete stop. Believing it was fully secured in Park, I turned my head to check on my child in the back seat and naturally released the brake pedal completely. However, the system had actually rejected my command. I assume that the vehicle likely still had a small amount of speed at the exact millisecond I pressed the button, and the computer automatically blocked the “Park” command and kept the car in gear. Because an electric vehicle operates in almost complete silence, with no engine noise or vibration to indicate that it is still in gear, there was no auditory or physical cue to alert me that the car was moving when I released the brake. While my attention was turned toward the back seat for a few seconds, the car quietly began to creep forward, leading directly to the collision with the car in front of me. Following the accident, I found that the vehicle produces slightly different sounds when Park is rejected and when it is successfully engaged. However, the owner’s manual describes only the dashboard message and does not describe these sounds or explain how to distinguish them, so their meanings may be learned only through the failure. At the time of the incident, I was not familiar with the distinction between these two sounds. Because my brain processed the physical press of the button as a successful action, and I had visually confirmed that we were not moving, my focus immediately shifted to my child. I was entirely misled by the digital interface.
NHTSA ODI 11749766