I usually fill mine just before or right at the point that the low fuel light goes on. I am usually somewhere in the vicinity of 215 miles at that point. The on board computer indicates that I get 16.3 mpg (reset about 6 months ago). I have a 2000 S (3.2). Yes, it is expensive for an everyday driver. Remember when we though $1.25 was expensive for a gallon of gas? Oh for those days. But it is so much fun to drive that I add entertainment value to it and I think I come out waaaaay ahead.