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Discussion Starter · #1 ·
Not another evic is off thread.
This one is different, my last 2 fill ups my display has been off .5 and. 4mpg but the other way. Display says I got 23.8 hand calculation says 24.2. Yes I am resetting trip each time and I know how to hand calculate.only small variable would be I squeeze as much fuel as I can in without spilling so each fill may vary by a tenth of a gallon or so.

I'm not complaining just commenting.
 

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its pretty impressive if you ask me. On all of my previous ram trucks (2500/3500) they were off by 5 or so MPG. they would say 19 when really getting 13/14. Ive never paid much attention to milage, but did check it a couple times, and thats a common thing on all the heavy duty trucks from what iv'e heard
 

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Hand calc on any one tank can have margin of error. However hand calc over many adjacent tanks is the most accurate by far. I hand calculated EVERY tank of my Mercedes car, always complete fill-ups, and it's computer was consistent high by 0.5 to 1.0 mpg. It was good for trending, but not for accurate fuel consumption. I will track every tank of my truck because I know it's off, and high, by about the same as my car.
 

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Just returned from a road trip covering 3855 miles, towing a *lightweight travel trailer, mixed interstate and state hwy driving.Basically through WA, OR, NV, UT AND AZ. EVIC average 19.8 mpg , calculated mileage 18.7 mpg. So EVIC was 10% optimistic on average. Looking at the individual fill-ups receipts I found the EVIC to report from 4% higher to 19% higher. So my EVIC appears to be all over the map. Having said that I am more than happy towing while getting an avg of 18.7 mpg. That is 50% better than what I got on the Tacoma,
I confirmed that the DEF consumption was significantly higher when towing, have not kept exact records but added 5 glns when I got back at odometer reading of about 4800 m brought the gauge indicator to 3/4 full.

* I rolled over a DOT scale in Utah which indicated a total GVW of 9500 lbs (truck + trailer).
 

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Discussion Starter · #9 ·
I just thought it was interesting because they are normally optimistic and mine was a pessimistic. I'm happy with how close it is. Just found it interesting it is off the other way from what they normally are. And I always had calculate. My old Toyota gas gauge didn't work and it didn't have a resetable trip so I had to pay very close attention to fill ups and mileage. I was wrong twice and had to hike it.
 

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Just returned from a road trip covering 3855 miles, towing a *lightweight travel trailer, mixed interstate and state hwy driving.Basically through WA, OR, NV, UT AND AZ. EVIC average 19.8 mpg , calculated mileage 18.7 mpg. So EVIC was 10% optimistic on average. Looking at the individual fill-ups receipts I found the EVIC to report from 4% higher to 19% higher. So my EVIC appears to be all over the map. Having said that I am more than happy towing while getting an avg of 18.7 mpg. That is 50% better than what I got on the Tacoma,
I confirmed that the DEF consumption was significantly higher when towing, have not kept exact records but added 5 glns when I got back at odometer reading of about 4800 m brought the gauge indicator to 3/4 full.

* I rolled over a DOT scale in Utah which indicated a total GVW of 9500 lbs (truck + trailer).
Well, they thing is you can't say say for certain what percentage it was off each time. Every pump is different as to when it will shut off due to the back pressure. Hand calculating isn't perfect unless you use the same pump at the same station every time. The EVIC is probably off, but your hand calculations are probably off too.
 

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Discussion Starter · #11 ·
Well, they thing is you can't say say for certain what percentage it was off each time. Every pump is different as to when it will shut off due to the back pressure. Hand calculating isn't perfect unless you use the same pump at the same station every time. The EVIC is probably off, but your hand calculations are probably off too.
Good point
 

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I agree that the hand calculation is not an exact art, even when getting a fill-up at your usual pump. On the 12 day road trip I probably hit 14 different pump stations, for that reason I think the average values that I calculated are reasonably meaningful. I have a feeling that when towing the EVIC is less accurate as compared to driving the truck only. I will start doing the non-towing test starting with my next fill-up.
Does the system rate the fuel consumption by the amount of fuel being delivered through the fuel pump? The fuel system employs a fuel return line and when towing,much less fuel would be returned as compared to when driving solo. Perhaps the EVIC is calibrated with a return flow rate based on driving solo. Ideally the flow rate would have to be monitored on the injector side of the fuel distributor, which I imagine would technologically be more of a challenge, however it would provide accuracy under all load conditions.
 

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If the evic or any other brand car was measuring actual fuel flow, it would be dead on accurate. I'm guessing they are using algorithms of other inputs. The hand calc is going to be most accurate by far. Not a worth using same pump each time. Fuel pumps are certified accurate. The issue they say is that with ANY ONE fill up, foam and air may cause the pump to stop pumping too early and not consistently. This is a non issue however when you manually hand track and calc all adjacent fill ups. Over three or more hand calculated fill ups, you are exactly accurate. The on board computer is good only for trending under similar conditions.
 

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When in the EVIC Fuell Econmy screen (not the A or B trip computer screen) is displaying "Average MPG", this is a rolling average of the past how many miles? 100 miles? 500 miles? It obviously is not the mileage since the last time it was reset since this number would barely change after a fair numbers of miles were logged.
 

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Yes it is a rolling avg... not sure exactly how far back it goes, but I noticed it too
 

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When in the EVIC Fuell Econmy screen (not the A or B trip computer screen) is displaying "Average MPG", this is a rolling average of the past how many miles? 100 miles? 500 miles? It obviously is not the mileage since the last time it was reset since this number would barely change after a fair numbers of miles were logged.
Since the last time you held the right arrow
button on the steering wheel to reset
It . The arrow is right there
On the screen for right arrow to reset.
 

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I realize that it can be reset with the arrow key, but it is most certainly using a rolling or moving average. The MPG is just the distance "x" of the rolling average divided by the amount of fuel used over the last "x" number of miles. The question is simply what is "x" in miles? My guess is it is something like the past 50 or 100 miles traveled. Perhaps it could be time based as well, but I doubt it. I have searched the owners manual and google, but have not arrived at an answer.
 
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