Of course, this isn't the first site to track your fuel economy numbers online, just the most slick. The classic EPA site Fueleconomy.gov will not only track your MPG, but will also add that data to numbers from other users and then be able to provide a real-world MPG estimate for car shoppers. I heard about My Milemarker from Autoblog, and a commenter there says that BrianBauer is his option of choice. Whatever your method (online, calculator, pen and paper), knowing your fuel economy numbers is a great way to think about driving greener.
[Source: MyMilemarker via Autoblog]