I'm curious...everyone has the fuel guage light that glows yellow when you're getting near empty, right? Mine goes off right at the "F" line, but I've noticed that when I fill the car up, I can only fit 11 or so Gallons into the tank(It holds 13 gal.)-What amount of Gas should be in the tank for that light to go on? Is it like 2 gal. or something?