My owner’s manual says the gas tank holds 16.5 gallons. Every time that I have run the gas low and the fuel light comes on, the most gas I am able to put in when I fill up is around 12 gallons. That’s about a 4 gallon difference. Do I really have 4 extra gallons of gas or is that just a misprint?
That’s probably about right. It’s not very good for a modern car to run completely out of gas, so carmakers factor in pretty big fuel reserves to make sure it doesn’t happen. Also, just because the liquid capacity of the tank is 16.5, that doesn’t necessarily mean all of that is usable-- you have to figure that by the time you’re at your last gallon or so if the gas is sloshing around, it can slosh away from the fuel pickup. Also, the fuel pump, gas gauge sender, and the various other parts that are in your gas tank these days also take up some tank volume.
So figure they don’t want you to get below 1 gallon or so, the equimpent in there maybe takes up a half gallon and you’re left with three gallons which if you’re a real lead foot might get you as little as 50 miles and that’s usually about the range they like to leave you once the gas light comes on.