CHICAGO – has compiled a True Mileage Index to rank automakers by fuel economy. The True Mileage Index analyzes a number of factors, including combined city/highway EPA gas mileage ratings, vehicle sales, an automaker's lineup of vehicles and more to determine major automakers' average gas mileage across their lineups. As a result of not giving allowances for alternative fuels or other factors, this number will more accurately reflect the mileage consumers can expect from their vehicles, according to

The full index is available at the Web site.