If you do not drive it like youstole it, you should get about 300 miles per tank. The gas gauge is pretty useless. When I fill up it tells me all kinds of numbers to empty and I can drive 50 miles and still have the same number to empty. I keep meticulous numbers on my GTs and the best way is to track the miles per tank, unless you want to fill up all the time. Certainly at 250 miles per tank you should think about filling up.