The Fusion is a hybrid electric vehicle by Ford. It runs on a gasoline engine but has a battery and can run an electric motor off of it. It has regenerative braking to avoid the total loss of fuel when slowing down and stopping. I think one of its most interesting features is the advanced control panel, which shows you the exact state of the engine at all times. You can clearly see the mileage you are getting along with the contribution of the electric engine. This kind of situational fuel efficiency awareness is critically important to providing the feedback which allows people to improve their driving habits. And the driver is the most important factor of all for saving on gas.