I have a 2015 Energi with less than 6,000 miles on it. I have read all the above posts, but have to admit most of the replies are above my head technically. I was just coming back from a trip and got stuck in bumper-to-bumper traffic for 2 hours. After creeping at a snails pace and finally getting through a toll plaza I proceeded to cross over a bridge that has a slight incline at the start. My Energi's transmission whined and slipped and I had no power whatsoever. Thank goodness I had a passenger with me who instructed me to feather the gas, down shift to low and then try to shift back up to drive. This seemed to get me back on track and I finished the rest of the drive, 2 additional hours, without incidence. I brought the car to service and they could find nothing. I find it hard to believe a new vehicle had such a malfunction and there's no trace. Any non technical suggestions would be appreciated. Thank you.