The gas tank has a peculiar shape. Which is one reason to fill up as soon after the low fuel light comes on. The most I have driven after the light came on is about 25 miles and it took 14.X gallons. The book says it holds 15.9 gallons but don't try for that.
In cross section, the tank looks like a catamaran boat. There is a jet pump (like a venturi) that is used to take fuel returning from the engine to produce negative pressure in the pump. That pump then transfers fuel from the sub-compartment of the tank to the main compartment where the "real" fuel pump is located. I'm old enough to remember "Rube Goldberg" and it reminds me of some of his "inventions".
Remember this before you try to go for 15.8 miles on a fill up. I have never had a problem aiming for a 13 to 14 gallon fillup. So, it works OK by my standards.