[AeroModder]

Awesome! but did you remember to check where the needle was on your gauge the last time you filled it, and compensate for the difference after the next fill? The pumps never "click" at the same amount, so if you don't correct for that, it'll either inflate or deflate your numbers. Over a long-term fuel log, you'll get an accurate average by writing down exactly how much was added, but for a single tank, you have to compensate for the amount of fuel between "clicks."

Also, with such a low amount of fuel, it's extremely hard to get an accurate MPG measurement. Just an extra 0.32 gallons to make 1.5 drops it down to 41.6 mpg.