A free program for Android, by William D. Kraemer.

If you want to know how much fuel you’re using, or how efficient your car’s engine is, you need to keep a log of the amount of fuel you buy, and the distance you drive. With the FillUp app, you can do just that. 

How does it work?

The first thing you need to do is select the unit of measurement. There are two options available: gallons per day (US) or liters per day. The next thing is to enter the amount of fuel you purchased. This can be in gallons or liters. Finally, you need to enter the current value of your odometer.

You will get a result that shows how much fuel you need to drive in order to get from one point to another.