Fuel Economy

[BMGYaris]

Originally Posted by regulus

so best thing i guess is start counting from the second bar until the 7th vanishes. Ill try that

I never meant to ignore the first bar in your calculations. I just meant that the gas fuel guage is not precise, it is just rough estimates as to how much gas is still left in your tank. Thus no bar or number of bars represents exactly what it does mathematically (mathematically each bar equals 1.387 gallons, but in reality it will not drop at that precise moment). Suppose that on your first bar it was off .21 gallons off. that would be something about 15% more fuel consumed than what you mathematically yield should have been used on your first bar. But the more bars that are gone then the less the margin of error impacts your calculations.

So what this means is that on one bar the margin of error is going to represent some range of fuel consumption, lets say anything from 5-25% more than what you would expect that first bar to actually represent. However, as you use more gas, the actual margin of error (say .21 gallons) should remain pretty consistent (within a range). That means that if .21 gallons creates a 16% inaccuracy when guestimating from your first bar, you will find that the % inaccuracy decreases as your fuel consumption increases. Thus as the total gallons consumed increases the error will represent a smaller portion of your gas consumption. Meaning the more gas consumed the more accurate your bar guage will be, though no one particular bar will be any more accurate than any other. You should always calculate with all available information

Note: im only talking about rough guesstimating before fill ups. Obviously the only way to get true readings is to fill up many times at the same pump. I just didnt want him too be too shocked when his 35 mpg city turned in to 29 or 30...hopefully 32.