Quote Originally Posted by SJAndrew View Post
The only variable that your can change to increase your MPG any significant amount is your driving style and or engine/drivetrain. Crappy gas versus premium, oil/fuel additives etc will only change your MPG within the margin of error.
I agree on the whole doing the math part of figuring MPGs over trusting the dic.

But there are MANY factors that can mess with your MPGs. CPS, Too hot or too cold of plugs, bad plug wires, bad coils, clogged fuel filter, bad or weak fuel pump, seized brake calipers, I could go on and on.