I've taken several (freeway) trips and calc'd mpg by gas purchased/miles driven and the actual is always ~10%-12% less than the EVIC report for the trip.

I see a LOT of people reporting their mpg from "computer" which I assume is the EVIC - is it only my EVIC that is so far off????

Is there anyway to adjust the EVIC mpg figure? It would be nice to have an accurate calculation of Distance to Empty for instance

2009 RAM 1500 w 4.7L, 2WD

 

my evic has never been off by more than .5 of a gallon, andi always hand calc.

 

The farther you get into the gas tank, the more accurate it will be.

I find the DTE very close. Especially near the end

 

Mine is close to 1/2 mpg off from the EVIC which is no big deal to me.
How much difference are you seeing compared to real world mpg..?
Might suggest having your dealer maybe reflash yours for you..???
In any case, dont put too much faith in those EVIC mpg numbers,
ther`s a good reason why most of us call them "Lie O Meter`s"
I do find, that my "DTE" is right on the money though.

 

1 freeway trip round trip Sacramento to Santa Clara, 99% freeway driving, 265 miles total distance - I calculated 22.5 MPG based on gas and mileage, EVIC reported almost 25 MPG.

Truck is stock, speedometer is dead on (checked vs GPS) mileage never calibrated, but I know the mileage on the Sac to S.Clara trip is the same as my wife measures in her car, and also in my old truck (+/- 1 mile each way)

I get similar % difference around town

Can dealer "flash" it to more accurate numbers?? Or even to put a -10% fudge factor in?

 

My EVIC is usually about 1 mpg higher than what I calculate by hand and I calculate it every time I fill up.

 

Mine is off by at least 1/2 mpg, even after compensating for the tire size. On the spreadsheet I use, I have both, hand calc and what the EVIC reads. There's been a few times they were close and once the EVIC read below what I got.

The one in my wife's Ford Edge is pretty much the same way, tho.

 

Similar experience. the EVIC readout is generally high by 1 mpg or less. It is more accurate the more miles I have before fillup. Also have to remember its an average mpg. Also have to remember to reset each time I fill up.

It is also my opinion that even though I fill up till the gas nozzles click off, that full gallons may not be the same each time. My point is if the fill up if even off a gallon can make a difference. as an example

300 mile trip , 17 gallons to fill up , = 17.6 miles per gallon
300 mile trip, 17.5 gallons to fill up = 17.1 miles per gallon
300 mile trip, 18 gallons to fill up = 16.6 miles per gallon

So even hand calc, my opinion is even when I fill up, I may not be starting out with the exact total gallons in the tank as the last time. Being off even 1 gallon can make a difference in mpg.

Bottom line, the evic is an average. Not an exact mpg.

 

You mean when I reset it and coast down hill for a while I am not really going to get that 38mpg it displays for the whole tank? LOL just kidding. I used to have a spreadsheet that used every tank, but I stopped using it. It was getting a little too depressing.

 

Up here in Canada, they are advertising Hemi trucks getting 28mpg on the highway (23mpg).

I don't think there is a (down) hill around here long enough to see THAT number!