Fill Up Tracker
Fill Up Tracker is a Simple, Free, Ad-Free app to help you keep track of your MPG. Simply enter in your trip, or odometer reading, and how much you filled up at the pump and let Fill Up do the rest! Optional to track the locations of your fill ups.
The built in calculator helps you plan better. Enter in the price per gallon and how far you need to go and Fill Up Tracker will estimate how many gallons you will need and the cost of the trip.
Fill Up Tracker is available for the iPhone or iPod touch, and is Free in the App Store.
Download it here.