General Motors already offers a "mild hybrid" version of its current Saturn Vue. "Mild" means that the low-power system can't actually move the vehicle, but it does provide assistance during acceleration. And it allows the Vue Green Line's engine to shut off entirely whenever the vehicle comes to a full stop. That saves the fuel that's normally wasted in idling.

The main advantage is that the "mild hybrid" system costs less than the "full hybrid" systems offered on other vehicles.

The redesigned Vue, coming later this year, will offer that system as well. Later on, however, it will also be available with GM's "two-mode" hybrid system.

Later yet -- there's no announced date for this -- GM has promised, a "plug-in hybrid" Saturn Vue will be available. It would be a two-mode hybrid vehicle with the addition of a plug so the n Vue's batteries could also be charged from a wall outlet.