How accurate is your MPG monitor?

2ndChance

According to the MPG monitor my car averages 13.6mpg.

But after taking note with several fills, 5 gallons of 91 fuel would only get me 58 miles tops, that's about 11.5 mpg. I do some heavy driving but most of the time I'm stuck in traffic. Average speed 17mph .

Just wondering how accurate are yours.

Chan Chee Hoe

Mine very accurate,only the distance to empty is worrying sometimes,it begin on 75km to empty,then 3-4 km later,it reads-------.!

whealy

I wonder if "the computer" is disreguarding idle time. That could explain your difference. I'd be curious how close your numbers would be on a constant run.

WhiskeyHotel

The computer really shouldn't be discarding idle time.

Mt Tam I am

I do not think mine represents an accurate picture either.

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Dark Sarcasm

i dont think its designed to tell you exactly what you are running. Its an indicator of "how" you are driving. Also, i think it averages all your mileage, if you reset it on a regular basis it will be more accurate.

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wax

Jack370Z

Here is the description from the Owner's Manual...

Average fuel consumption (MPG or l
(liter)/100 km) and speed (MPH or km/h)
Fuel consumption:
The average fuel consumption mode shows the
average fuel consumption since the last reset.
Resetting is done by pushing the switch*B
for longer than 1 second. (The average speed is
also reset at the same time.)

The display is updated every 30 seconds. At
about the first 1/3 mile (500 m) after a reset, the
display shows “——”.

So, it is just an "average" based on the last 30 seconds or so of driving. Mine has been awfully close to the actual computations when filling up. Of course, I round off to the next increment ($$) so I probably don't get an exact read on gallons I put in.

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Jack 09 370Z

hdskull

Mine is very accurate, no more than .1 off. It does take into account idle. If you turn your car on and leave it there, you'll see the MPG meter go down.

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c41006

I say reset everything and you should find it to be very accurate

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Dark Sarcasm

the display is updated every 30 seconds, the average is from the last time the driver pressed reset. If you reset it and drive you will notice drastic changes in mpg at first in relation to acceleration and deceleration or idling. After driving for a while it starts to average out and changes very little.

OP, track your miles and fill ups and reset the mpg at each fill up. I get 21 - 22 mpg and I have a heavy right foot, and twitchy left hand on the paddle.

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wax

happytheman

When I first picked up my Z (used) I was surprised to see the average was 18.1 mpg, but after resetting I regularly see 28 mpg with a 75-25 mixture of highway-city driving.

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--Brantly--

sonic370

once it hits 50 miles and starts to flash it averages 4 miles a gallon by the
computer................

Nismo89

mine says im averaging (highway) about 29-30 mpg, so pretty accurate for me

christian370z

Mine is pretty accurate as well in most cases, however there are times where the car says 100 miles left on a 1/3 of a tank and so and then I do a WOT pull and all of a sudden, I only have 2 fuel dots left and less than 50 miles haha. Who knows, but it is pretty much spot on in most cases.

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TypeOne

Mine is sorta accurate... I'm never driving the same so it's hard to see a consistent reading.