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My dash reading, on average, has been within 0.5% of actual since I got the car but over the last few tanks it appears to be indicating higher by almost 5%. Maybe it's just the type of driving I'm doing now and will go back to normal when my driving is back to normal. I should say that the abnormal driving is due to prolonged periods of very high mpg, like 45mpg+ and it may be that at the high end it calculates too high.


Brian
 

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Mine usually reads about 1-2mpg higher than calculated in my regular mixed driving. However, it seems to be close to dead on if I'm doing a lot of continuous highway driving on a tank, without starting the car a lot for separate trips.
 

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Over the course of my last 10 fill-ups (always 10-11 gallons), I've had mine read from 1-3 mpg higher or lower than actual. At least 8 of those fill-ups, the computer is indicating higher than the actual calculated mileage.
 

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Over the course of my last 10 fill-ups (always 10-11 gallons), I've had mine read from 1-3 mpg higher or lower than actual. At least 8 of those fill-ups, the computer is indicating higher than the actual calculated mileage.
The Rolling Average Fuel Economy (RAFE) is set (at the factory) to look at the last 1000 km.
When you reset your RAFE, you can see instantaneous fuel economy for a short while, until your RAFE starts having big numbers to divide by.

The accuracy seems close, but slightly low for my driving habits. I'd say -2.5% in my case.
 

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2-3 MPG more than calculated. I have seen this discrepancy in every vehicle I have owned with this sort of display.
 

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I agree. I noticed the same thing when I traveled 3000 miles a few months ago. 2-3 mpg difference. Still is not bad when you think of it.
 

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The thing that's alarming is how fast the "Miles to go" part of the display drops as the tank gets closer to empty. I have driven several miles on "0 to go" and then put ten gallons of gas in to fill it.
 

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For normal mixed driving, I find the display registers 2 mpg above my hand-calculated mileage on average. However, for longer "straight highway' tripe, I've found that the display actually registers 1 to 3 mpg below my hand-calculated mileage.
 
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