How can I reset average fuel mileage?

ellykay

Member
How can I reset the average fuel mileage between fill-ups? I can't figure it out, so I am not getting a good reading on the mileage. I will do it manually, but I figure there has to be a way to electronically do it as well.
 
Just hold in the "info" button until it beeps. You need to be displaying the average fuel economy while doing this.
 
Pressing info button repeatedly cycles through several parameters on the display at the top of the dash (not the navigation screen, in case you have that). When either avg. mph or avg. mpg are shown, holding the info button for a few seconds will reset it.

Be careful, though, because the avg. mpg readings you get from this thing are usually a few mpg too high. I have recorded both this readout and the same thing calculated by hand (miles from trip odometer divided by number of gallons filled into tank) at each fillup for three years (in my ms3), and the computer method is consistently higher (reports better gas mileage) by 2-5 mpg. After only a couple of tanks with my 2010 CX-9, anecdotally it appears to be the same.
 
I've found the average mpg computer on my 2009 to be pretty good. Never more than 1 mpg too high. Pretty good as far as these things typically go.
Anyone know how the computer calculates avg speed? Is it total miles divided by time moving? Total miles divided by time that the car is turned on? I can't figure it out...the numbers always seem incredibly low.
 
Fuel economy gauge

Well, after a few more fill-ups, I'm finding the CX-9 "info" reading to give me readings between 0 to 1 mpg higher than the old "miles driven divided by gallons filled" method. This is significantly better than the same gauge does on my MS3, where it is consistently 2-4 mpg higher. Don't know why they would be different, but the CX-9's gauge seems to be more accurate.
 
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