While driving in the left lane of the interstate at 70 mph, the engine abruptly shut off, shifting the car into neutral. The dashboard read start engine, which did not compute immediately. I quickly navigated to the right lane to assess the situation and eventually to the shoulder of the highway where I parked the vehicle. I was unable to to restart and had the vehicle towed to the dealership. It took ~6 hours for the Onstar tow service to arrive.