Miles per gallon
Key: R = revised.
Note: Dimensionally, fuel economy is miles divided by gallons. Then, presented with more than one fuel economy value, an approach to averaging the values is to compute the result by determining the total miles traveled and dividing that by the total gallons used.
Source: U.S. Environmental Protection Agency, Light-Duty Automotive Technology and Fuel Economy Trends: 1975 Through 2007, Table A-2, available at http://www.epa.gov/otaq/fetrends.htm as of September 2007.