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MPG values shown on the tire are miles per gallon of gasoline equivalent (MPGe). Non-liquid fuels, like electricity and hydrogen, are not measured in gallons, so using conversion factors allows them to be displayed on an energy-equivalent basis using the familiar MPG measurement. For example, an electric vehicle with fuel consumption of 30 kilowatt-hours/100 miles has a fuel efficiency of 112 MPGe (based on the conversion factor of 33.705 kilowatt-hours/gallon of gasoline equivalent).

Certain scenarios will increase, rather than decrease, GHG emissions. For instance, if you select an MPG that is below today's average fuel economy (22 MPG), you are selecting a fuel economy that is worse than today and will result in increased emissions compared to today's emissions levels. You can offset those emissions through activity or fuel-GHG reductions, or by increasing fuel economy.

Examples of how different fuel economy levels could be achieved:

• 40 MPGe
  • Gasoline vehicles are improving every year due to federal fuel economy and GHG emissions standards. The tire starts at 40 MPGe because new vehicles are projected to get about 40 MPGe in 2025 due to the these standards. Learn more about fuel economy and GHG standards.
• 50 MPGe
  • Gasoline vehicles are improving every year due to federal fuel economy and GHG emissions standards. New vehicles are projected to get about 40 MPGe in 2025 due to these standards.
  • If vehicle fuel economy keeps improving 2% each year after 2025, we’ll hit 50 MPGe by 2050.
• 100 MPGe
  • Almost half of all cars and trucks are plug-in hybrid electric vehicles that run on both gasoline and electricity while the rest are hybrid vehicles that just operate on gasoline.
  • The use of strong lightweight materials cuts the weight of new vehicles in half and both wind and road resistance are significantly reduced through improved aerodynamics and better tires.
• 150 MPGe
  • Hybrid cars running on gasoline could hit 150 MPGe if vehicle weight is reduced by 75%, road and wind resistance are halved, and engine and drivetrain improvements start to approach their realistic limits.
  • A fleet average of 150 MPGe could also be achieved with less extreme—though still very aggressive—improvements if most cars are all-electric vehicles.

Visit EPA’s Green Vehicle Guide to find the most efficient cars that meet your needs today.

*The average fuel economy of today’s cars and trucks is about 21.6 MPG according to recent highway statistics. (See the 2013 Highway Statistics, Table VM-1, available at: http://www.fhwa.dot.gov/policyinformation/statistics/2013/vm1.cfm)