That is one of the things that really bugs me about my T4R, but I have learned to just live with it and laugh at it. My gauge goes full retard sometimes, like showing beyond empty with the reserve light flashing right after I fill it up, or showing full when it is almost empty. The reserve light almost always comes on when I have about 7 gallons left in the tank.
I haven't felt motivated enough to fix it, which involves some money and a fair amount of work. If I have less than 300 miles on my tank, then I don't worry too much about it, because I know that once I shut it off and turn it back on, it usually reads correctly.