I don't know all the ins and outs either but it's a TWO MODE hybrid powertrain. I believe they CAN be a "full" hybrid at low speeds but they will also provide electric boost while cruising at higher speeds. It sounds like they'll provide more electric boost at cruising speeds than any current hybrid set up out there, from the way GM gloats about it improve highway fuel milage while some other hybrid powertrains really don't have much affect on highway milage. GM thinks this will be the model everyone else will follow, as they think it's superior to the other hybrid systems out there.

I keep reading "it'll save atleast 25%", in trucks and SUVs thats "A LOT" of gasoline, maybe the mpg increase isn't as much as a compact car but it sounds like the percentage of mpg increase should be close.