I think most ppl get around 300-350 miles on 1 tank of gas, 60 miles would be 1/5 to 1/6 of a tank then. It doesn't sound right that the light comes on solid with 1/5 to 1/6 of gas left. (Mine stays on after the needle falls below "E")
My guess is maybe 40 miles from light staying on till the car dies out of gas, but I never tried that before. I'd go to the gas station at most 20 miles after the light stays on.