If I'm reading it right dual mode refers to "Stealth mode" or ICE off "electric only" mode. The system sounds basically like the one in the Prius as opposed to the one in the Hondas. Hondas do not have an "electric only" mode.

I have zero confidence on GM or any US auto maker to come out with anything worth a crap, unless it a copy of a Japanese car. Quite a change from when the situation was exactly reversed in years past.