We were driving down the interstate at around 70mph and without warning — the vehicle shut off. The engine stopped running and the vehicle put itself in Neutral. The headlights and electrical all shut off and the only message on the display was to push start to restart the vehicle. Luckily, we were able to safely maneuverer out of traffic without being hit by other vehicles. Our vehicle was able to be restarted once we came to a complete stop and put the car in park. We are having he vehicle towed to our local GMC dealer to have it evaluated. The issue only happened one time.