I had the same thought, because after filling up my display has been resetting to 530 miles (my mileage has varied between approx 35 and 38 mpg). Yesterday, the display showed 0 miles and the warning light came on even though the needle was midway between 1/4 full and empty. This would not have concerned me before I read kdhspyder's post describing how his Prius may have shut down because the car thought it was about to run out of gas and didnt want to damage the battery.