How fuel efficient is your vehicle? Do you ever get the suspicion, as I do, that your car's gas mileage is getting worse? Have you ever wondered how your mileage compares to other drivers? And what about the estimated mileage touted by the car companies? Does a Mini Cooper really get 37 miles per gallon?

Matt Haughey and Paul Bausch have launched a new site called Fuelly, which allows users to track their vehicles' fuel economy and to compare data with other drivers. As you enter data for each fuel up, Fuelly tracks your average number of miles per tank, your average cost per tank, your fuel efficiency, and more.

If you'd like to compare information with other users, you may:

• Browse cars (there are currently 1369 vehicles being tracked at Fuelly)
• Pick up some tips on fuel economy
• Participate in the discussion forum
• Add other users as friends (I'm jdroth, as always)

Fuelly is brand new, so data is scarce. Over the next few weeks, however, users will fill their tanks, and then people will then be able to compare mileage and track their own vehicles' performance. (For a preview of extended data, check out dredpyrate's 2004 Mini Cooper, which has data all the way back to the first of the year! It gets 32.8 miles per gallon.)

I think this is a great idea. Fuelly taps the power of the masses to compile real fuel efficiency data so that users can find ways to save money. Brilliant. Because Fuelly is new, it is not without bugs. Haughey and Bausch promise to squelch these soon, and to add new features, such as metric units and support for additional vehicles (like scooters and uncommon cars).