Re: Fuel tank and MPG confusion
I calculated my mileage for an entire year. By the pump, it was 46.36, by the computer it was 46.99. This makes the computer 1.4% optimistic. But, gas pumps are not perfectly accurate. So, all I can say is that the two are very close. After 10,000 miles they differed by only three gallons, $12.00, not very much in the total cost of driving the car.
I ran my tank dry once and got 10.9 gallons in. In very cold weather I will get less than seven gallons in after the last square is blinking. Also, in the winter the first square goes out after 15-50 miles, in the summer the first square goes out after 70-160 miles.
The gas gauge measures the level in the tank. In cold weather, the top of the bladder does not expand. The one thing that the gauge is quite good at is warning: when the last square is by itself, start looking for gas; when it starts blinking, get gas.