I had a 96 Grand am several years back, my brother and I were out driving around, the car died on us, ended up being out of gas, yet the gauge showed between 1/4 and 1/2 a tank
After that I had a 72 GMC sierra grande that had a non working gauge so I ran out of gas in that every 2-3 weeks, on a good day, that truck would get about 7mph it averaged 6mpg though, that sucked bad LOL. now with my aveo I average about 320miles a tank 32mpg is pretty good, with all highway on a tank I get about 37mpg