You always knew your vehicle’s EPA ratings were different than your real world mileage. Now www.fueleconomy.gov, the Web site run by the U.S. Department of Energy and Environmental Protection Agency, allows you to compare the two. With “Your MPG,” users can track their real-world, on-road MPG for multiple vehicles, share the data, and compare their averages to EPA test ratings. The submitted data is compiled into city, highway and combined MPG averages for a wide range of makes and models. Registered users can keep an inventory of their vehicles and access tools for recording, calculating and updating MPG information for each vehicle. Users can also track fuel purchases or download forms for manual data entry. Visit www.fueleconomy.gov and click on “Calculate and Share ‘Your MPG.’” The Web site has recently posted the EPA fuel economy ratings for many 2007 models. In addition to gas mileage, nationwide gas prices and alternative fuel technology are also featured.