So this happened to me yesterday afternoon, driving on the 80 West near Truckee. 18-wheeler was tootling along at 60mph in the fast lane (illegal), with 75mph traffic flow otherwise. In California it is legal to pass on the right. So... Be careful out there, people!! FWIW, my car does not have Autopilot; I'm curious how Autopilot would have reacted in this situation. Also, my dashcam is a KDLINKS X1, highly recommended. Audio recording was turned off, or you would have heard me leaning on the horn from the moment the big rig started to merge.