Mileage Tracker is cool application which you can use to track your road statistics.

Mileage Tracker Features:

Miles Per Gallon: required I know total distance and total fuel used. (standard mpg value)
Gallons Per 100 Miles: no new information needed. (How many gallons does it take to make it 100 miles.)
Cost Per 100 Miles: I would have to also get price per gallon. (How much does it cost to travel 100 miles.)
Maximum Range: I would need the user to provide total gallons tank can hold. (How far could I travel on a full tank of gas.)

The menu has Clear, About, and Exit menu items that are all basically self explanatory.