What's the average of 5 MPG and 10 MPG?
The math isn't quite obvious to me, but if you go out camping and get 5 MPG on the way to the campground and turn around and get 10 MGP on the way back, your average MPG won't be 7.5 as you would expe...
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The problem with simply adding 5 to 10 and dividing by 2 is that that is indeed the average. But the real average is a weighted average.. So if you fill the tank,, Make the trip, use the unweighted average to predict how much you will need to re-fill the tank,, it will be wrong.
I use a combination of two things. one is the dash display (instant MPG which is calculated by measuring distance with the speed sender and time and gallons with the fuel meter and doing simple division) and by the "Miles since last fillup"/Gallons to fill, method.
Both are easy epically with modern smart cars and phones (Vehicle records "TRIP:" miles (miles since full) and phone does division).
I use a combination of two things. one is the dash display (instant MPG which is calculated by measuring distance with the speed sender and time and gallons with the fuel meter and doing simple division) and by the "Miles since last fillup"/Gallons to fill, method.
Both are easy epically with modern smart cars and phones (Vehicle records "TRIP:" miles (miles since full) and phone does division).
