While most modern cars will do this for you readily in their onboard trip computers, if you ever want to make sure what you’re seeing is what you’re actually getting, there’s a simple procedure by which you can determine how far your vehicle travels on each gallon of fuel it consumes.
To get an accurate picture of your fuel consumption, you’ll want to perform this following procedure a few times just to be sure your calculations are consistent. And actually, it’s a good idea to keep track of this on an ongoing basis anyway. Often an increase in fuel consumption can be indicative of another problem your vehicle has, which may have yet to fully reveal itself. By keeping track of your fuel economy on a regular basis, you can often notice problems developing before they become full-blown issues.