Truck? What truck?!
If I fill my car just after the low fuel light goes on, i usually get just over 10 gallons in there. That means that, for me, when that light comes on, at ~28 mpg, I could go approximately another 84 miles before running dry. But I don't do mpg calculations based on that.Our tank is 13.2? I get the light and no dashes and I fill up with 11 gallons.
You need to do some calculations with real numbers and not go by what you think or feel. Then you will know what kind of mpgs you are actually getting.