Lucky enough to have a company car furnished to me every two or three years, I learned to carry a small gas can (for a few trips) and deliberately run out of gas to see how far I could go after the light appeared you never know when it will become critical and it varies with each car also if and when you do, try removing the gas cap to release the vacuum which will allow a small amount of gas to flow and you will get an extra 1/2 mile or so.