The GasHog app tracks your car's fuel economy each time you fill up. When you hit the pump, simply enter your car's odometer reading, the amount of fuel added and how much you spent on gas.
GasHog automatically calculates the latest tank's fuel economy and compares it to past tanks. The app also offers tips for increasing how much your car gets out of each gallon.
The 99-cent app doesn't need Internet connectivity, and you can e-mail yourself backups of your past tanks' data.