Premature Warning lights for low fuel levels

Sorry, I know the last question was unrealated to the fuel warning lights, but wanted to get back to that subject, because that is why I am on this post.
That thing is driving me crazy too. I am glad to see that people have risked going past the 0 miles left and still have not run out of gas. I have an 09 and really like the car. I generally get 32 - 34 mpg, and no amount of hypermilling every seems to get me past 35 mpg. I know I could have gotten 50+ mpg with a Prius or Insight, but personally the less mpg is worth it for the style, speed and size of the NAH.
My warning light is on now, saying I have 19 miles left but I only have 523 miles on the trip. In the past, I have filled up when the light came on, but now, with everyones input, I am going to risk getting below 0 and see what happens! Those scary warning lights flashing in my face I can now ignore, which is darn near impossible, because know matter how many times you turn it off, it comes right back on after 1-2 miles.

I did it! I kept driving after the miles left said - - - . According to the car I should have been out of gas but I wasn't. However with the light coming back on and reading 0 miles left, and the fact that the needle was right on E, I did not want to risk it too long so I only drove about 5 miles before filling it. I was only able to put in 16.65 gallons when the hose clicked. I stopped there because I wanted to check the mileage. 33.04 mpg, a reasonable amount I believe because I did a few rapid accelerations on this tank and also drove the freeway 20-25% of the time.
So yes, the warning gas low light coming on early is a minor irratation, but I still think the car is great and have had it for a year now.

I have a 2008 Altima 2.5 SL, and i have the same problem, i average 480 to 500+ miles with a tank, which should be 20 gallons, but so far the max i could fill was a little over 18 gallons, which makes me think every time the light goes on i probably have left another 2 gallons in my car which would last me another 60 miles... I've tried finding answers in different places but i haven't. i'm probably gonna drive all i can and test it myself.