In 2011, Chevrolet unveiled the the futuristic Volt—a practical hybrid that supplements a plug-in electric motor with a conventional gas engine.
The hybrid combination operates in four modes based on range and performance needs. In purely electric mode, the Volt can travel up to 50 miles, or until usage reduces battery capacity to less than 20 percent. At that point the gasoline engine kicks in to regenerate electrical power and/or deliver power to the wheels.
In all-electric mode the Volt returns the equivalent of 93 mpg, a number that drops to 37 mpg in gasoline-only mode; combined fuel economy is 60 mpg. This makes it the most fuel-efficient vehicle with a gasoline engine sold in the United States.