I was just thinking - it could be that Nissan designs it's odometer to read under to avoid customers coming back complaining/sueing that their warranty ended sooner than the actual mileage - or to compensate for tire wear when the wheels will actually do more revolutions as they wear down for the same distance. Nissan could then figure that percentage back into the fuel mileage calculations. Does this all sound too farfetched?

 

OK - here's another way to do your calculations:

http://metrompg.com/posts/odometer-v...ogle-earth.htm

 

I have 25k miles on my TCH. I have a spreadsheet with all of my gas receipts and a log of what my MFD says my mileage was. I've also used the same pump at the same station for probably 90% of my fillups.

The issue here is precision and accuracy. Wikipedia has my favorite diagram (shots on a bullseye target) that explains the difference:

http://en.wikipedia.org/wiki/Accuracy_and_precision

Over 25k miles and 46 fillups my hand calculations are going to be accurate. But the MFD is much more precise.

In my case the MFD reads 1.2 MPG high.

All of my calculations are based off the odometer. Which I'm sure isn't 100%, but it applies to all calculations equally.

To get really good numbers the EPA uses a dynomometer to indicate miles driven and they measure the tailpipe for CO2 output to indicate how much fuel was consumed.

 

okay, I'm going to be the ninny here.

Do you need to reset soemthing to reset the MPG guage? Or does just reseting A and B on the odometer do it?

 

To reset the average MPG and average MPH gauge, you bring up these gauges (press the left button to cycle through the different displays), then press-and-hold the select button (the one on the right).

 

See Marianne! being a ninny is not so bad.

 

I'm still not sure I understand how to do it.

 

Hi Marianne,

I know you know this but I will try to help. The computer display that is right over your steering column shows different things depending on how many times you press one of the two square buttons on the dash to the left of the steering column. It will show you the temperature; average MPG bar, a list of warning settings and some other things. One of the settings shows your average MPG and average MPH since the last time you reset it. To reset it, bring up the average MPG and average MPH readout by pressing the (left with a bump?) button until you see it, then press and hold the (right) button until it resets. Press the left button until you are back to the setting you like. My wife likes the temperature.

I hope this helps.

 

My readout is consistantly 2-2.5 MPG higher than my manual calcs. Same pump, same fill rate etc...
The 3-4 gallon reserve is a joke. However, I'm sure Kraemer would get a "rush" out of it because he could drive 150 miles after the light comes on!!!

 

Well, it seems that we're all over the map (the range seems to be about +/- 2.5mpg), so I'll just wait for a few more tanks to get a better feel for how much mine is off.

In the end, it doesn't really matter, as long as the instruments are consistent; they're still useful for judging my mileage relative to other trips in the same car, and that's the most important use I have for them.