In the middle lane of a multiple lane highway, it suddenly gave a very confusing warning on the dashboard. It lost power and slowed down quickly to below 40 mph. It didn't help to press down the gas pedal. I was forced to switch from the middle lane to the passing lane in order to reach the shoulder. The car was side swept by another car in the passing lane because it was at low speed. Once it reached on the shoulder it stopped completely. If it gave a clear warning, for example, "pull out immediately!", and flashed the emergency light automatically, it might save a few seconds, and gave a warning to cars behind. It's a PHEV, and I believe that it used up the battery for driving but failed to automatically start the gas engine.