I just found Fuelly, and I immediately thought “Why didn’t I create this website?” Fuelly looks like a nice simple (and easy to write) site that allows users to track their fuel economy. It uses this data to generate histograms of mileage for any model of car with a sufficient number of entries. Of course, the answer to my own question is the similarity to the official DOE Fuel Economy site and its “Your MPG” feature. What seems to help Fuelly’s participation is the fact that instead of users independently calculating mileage then uploading the results, Fuelly lets users upload individual fill-ups and then automatically calculates mileage. To make this easier it has a mobile phone optimized site and a SMS logging feature to let users directly use Fuelly to record their fill-ups, eliminating the intermediate logbook that I use. Oh, and the animated SVG graphs can’t hurt. I’ll continue using my log, but this site looks like it will help a number of people.