Making a sustainable choice for your personal transportation is among the most significant steps you can take to shrink your carbon footprint and contribute to a more sustainable world.
A useful resource is the https://fueleconomy.gov website operated by the Oak Ridge National Laboratory on behalf of the U.S. Department of Energy and the U.S. Environmental Protection Agency. You can find MPG, environmental, and energy cost information on a specific vehicle.
This tool can help identify hybrid, plug-in electric, and other alternative fuel vehicles, as well as compare relative fuel efficiency.
The full tool and additional information are available here.