Quote:
Originally Posted by RedDevil
Forgive me if I'm wrong, but what really matters when adding up the MPG's is the number of gallons you put in......
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Hey, good point RedDevil. I completely forgot the effect of Miles Run per MPG, and it's affect on the calculation is significant.
Allow me to take another try at this, with appropriate units included for clarity.
Trip #1:
35miles/(70 miles/gallon) = 0.500 gallon used
Trip #2:
35miles/(130 miles/gallon) = 0.269 gallon used
Effective Consumption:
(35miles + 35miles)/(0.500gal + 0.269gal) = 91.03miles/gallon
One can see that the lower MPG reading over an equal or greater distance, predominates higher MPG readings. So it's important to improve lower MPG readings.
It's funny, but I have been focusing on improving mileage when it's warmer outside, rather than colder temps. From the above, one can see that it's more important to improve cold weather driving to save fuel.
My equation in post #1 is a little misleading because it does not consider miles driven as RedDevil pointed out.
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Sometimes it's useful to look at a situation in the extreme, so another example:
Trip 3:
98miles/(18miles/gallon) = 5.44 gallons
Trip 4:
44miles/(130miles/gallon) = 0.338 gallons
Effective Consumption:
(98miles+44miles)/(5.44gal+0.338gal) = 24.58miles/gallon
Quote:
Originally Posted by MetroMPG
Are we not just seeing the effect of using "MPG" as the measurement? Another example of why it's not an ideal way to talk about fuel consumption.
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Good point. The MPG notifier just considers the "final" energy efficiency, and not the number of miles driven in the calculation process.
Jim