The Aura Green Line, like the current Saturn Vue Green Line, uses a "mild hybrid" system. The downside of such a system is that it can't drive the vehicle, even at slow speeds, on electric power alone. The upside is that it's less expensive than a "full hybrid" system like that in the Toyota Camry Hybrid. The other benefit is that it uses a much smaller battery pack, so the Aura Green Line will have nearly as much trunk space as the regular Aura.