Not confused so much as trying to see how it makes much of a difference in real world MPG numbers. If this 10 mile trip is your daily commute, then the difference is at most 2 tenths of a mile. About 1040 feet per day. So for an average work week the difference is 1 mile. Either 53 or 54 miles total. Even if you did this on 1 gallon of gas, how much more gas did you burn? Is it even worth calculating? If you only averaged 30 MPG, the difference in what you used is only 3.3/100 th's of a gallon. Just a hair over 4 oz for the week. Less than a dime at $2.50/gallon for the week. Not much of a deal breaker.
For an average of 30 MPG, to drive the two longer distances, it would take either 33 gallons or 33.66 gallons. $1.65 extra to drive 1000 miles at $2.50 a gallon. Again, not a huge meaningful difference.
Precision is nice, but when converted to real world numbers, it seems like overkill.
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