The U.S. Environmental Protection Agency and the U.S. Energy Department have released the 2014 Fuel Economy Guide, which helps car buyers identify vehicles that are the most fuel efficient and emit the lowest amount of greenhouse gases.

The guide provides top 10 lists allowing consumers to see the most efficient advanced technology vehicles as well as the most efficient gasoline- and diesel-powered vehicles.

The guide lists the most fuel-efficient midsize cars as the Ford Fusion Energi Plug-in Hybrid and the Toyota Prius Plug-in Hybrid. Both deliver 58 mpg combined. With EVs excluded, the most fuel-efficient midsize vehicle is the Toyota Prius hybrid, which averages 50 mpg. The Chevrolet Impala eAssist is listed as the most fuel-efficient large vehicle, including EVs. The vehicle averages 29 mpg.

The website also provides an estimated annual fuel cost for each vehicle. The estimate is based on the vehicle's fuel-efficiency rating, and national estimates for annual mileage and fuel prices.

For the second consecutive year, the guide includes a 1-10 greenhouse gas rating for each model. The agencies will update the guide as more 2014 vehicles become available. View the guide at