In 2011, the EPA helped make used car buying a little more informative by creating printable gas-mileage window stickers.

Now, its effort to help used car buyers get fuel-economy information is going digital.

In addition to the printable fuel economy labels, the EPA has added a downloadable graphics that sellers can use in online ads.

Used-car buyers will now able to get a better idea of a car's overall cost of ownership whether they buy online or scour the neighborhood for "For Sale" signs.

All you need to do is head to FuelEconomy.gov, the EPA website that lists the gas-mileage ratings for all cars sold in the U.S. since 1984, and enter the year, make, model, and powertrain.

The tool works for every car listed on the site (except for plug-in hybrids and electric cars, whose efficiencies require more explanation).

Both the digital graphics and printable label include the EPA gas-mileage ratings (combined, city, highway) and CO2 emissions, adjusted to match new car fuel economy ratings.

There's also information about the vehicle, including its engine size, transmission type, and fuel type.

Also included is a QR code that links directly to the vehicle's FuelEconomy.gov page through a free smartphone app. This allows used-car buyers to get additional information, including the annual fuel cost.

The ratings are those from tests when the car was new; the EPA notes that fuel economy doesn't usually decline much over a car's lifetime--it's estimated at around 2 percent over 15 years--assuming it is maintained properly.

The labels include a disclaimer saying that estimates may vary based on variables such as how the car was driven and whether it as any mileage-sapping modifications.

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