The 2017 Ford Fusion Energi is powered by a 2.0-liter four-cylinder engine paired with an electric motor that's fed by a lithium-ion battery pack. The combined output of 195 horsepower is sent to the front wheels. The battery pack, which is considerably larger than that of the standard Fusion Hybrid, allows the Energi to reach speeds of up to 85 mph or to be driven up to 20 miles on electric power alone. That said, aggressive driving will cause the gasoline engine to start up at much lower speeds when the car is in its default EV Auto mode.