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Discussion Starter #1
Hi all,

I have been following the real time mpg readout on the EVIC for the last several tanks. Turns into a fun game trying to improve my mpg on my commute. I realize the avg MPG on the EVIC is a compilation of the last several hundred miles.

However, I've also been tracking my mpg on Trip A, and comparing with manual calculation of actual miles to actual gallons when I fill up. On my last two tanks the EVIC has been underestimating.

Tank 1 = EVIC 22.8mpg, manual calc 23.7
Tank 2 = EVIC 23.1mpg, manual calc 26.1!

I was pretty surprised to see that much of a difference in the last tank. Anyone else seeing this disparity? As an aside, I was super excited to see 26.1!
 

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variability of fill can make quite a difference in the manual calculation. Over 16,000 miles I see sometimes the EVIC is higher and sometimes lower. The overall EVIC and manual calc numbers are within about 0.3 mpg. Others on this site have said that the EVIC only keeps a running total for 200 or so miles and not for the full number of miles since the last reset. If that is correct the EVIC clearly cannot fully represent the overall economy of a 600 or 700 mile tank of fuel.
 

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variability of fill can make quite a difference in the manual calculation. Over 16,000 miles I see sometimes the EVIC is higher and sometimes lower. The overall EVIC and manual calc numbers are within about 0.3 mpg. Others on this site have said that the EVIC only keeps a running total for 200 or so miles and not for the full number of miles since the last reset. If that is correct the EVIC clearly cannot fully represent the overall economy of a 600 or 700 mile tank of fuel.
I've heard that here as well. How does anyone know it recalculates every 200 miles? Is that posted somewhere or in the manual?

BTW Howie Congratulations on your 1000+ post. You contribute a lot to this forum and I for one really appreciate it.
 

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Discussion Starter #4
The EVIC number listed above are for the Trip A report. That's a different number than the EVIC real time mpg summary, on the lower right corner of that guage. I believe that readout is the one that recalculates over the past 200 miles.

I assumed Trip A mpg was since I last reset the trip (in this case at the beginning of the tank.) Trip B has been up there for 2000 miles, and is a third number that differs slightly from the two mentioned above.
 

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The EVIC number listed above are for the Trip A report. That's a different number than the EVIC real time mpg summary, on the lower right corner of that guage. I believe that readout is the one that recalculates over the past 200 miles.

I assumed Trip A mpg was since I last reset the trip (in this case at the beginning of the tank.) Trip B has been up there for 2000 miles, and is a third number that differs slightly from the two mentioned above.
I am not sure there are three numbers but will have a look tomorrow. (I thought the average shown on the instantaneous was the trip A number but sure don't know it for a fact.) I'll have to watch it for a while and see if it different.I am quite certain that tboth A and B reset their calculation periodically but do not know what the period is. The reason I feel confident about that is how rapidly the number changes with a change in driving style. I had my trip A not reset by me for 10,000 miles and it still changes relatively quickly when you do a bit of spirited driving. If it didn't reset and was really showing a 9900 mile average a few 0-60 full throttle runs wouldn't change the mileage but it does.
 

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Discussion Starter #6
Good thoughts Howie, I see what you're saying. I know when I reset trip A the overall mpg is extremely variable initially, but then becomes less so the more miles accrued on Trip A.

Ahh, the mysteries of the Ram computer!
 

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I am not sure there are three numbers but will have a look tomorrow. (I thought the average shown on the instantaneous was the trip A number but sure don't know it for a fact.) I'll have to watch it for a while and see if it different.I am quite certain that tboth A and B reset their calculation periodically but do not know what the period is. The reason I feel confident about that is how rapidly the number changes with a change in driving style. I had my trip A not reset by me for 10,000 miles and it still changes relatively quickly when you do a bit of spirited driving. If it didn't reset and was really showing a 9900 mile average a few 0-60 full throttle runs wouldn't change the mileage but it does.
That's the same conclusion that I came to. Except for a glimpse at instantaneous fuel consumption, the EVIC, including trip meters, is pretty much useless.

Hand calculation over several tanks is the only way I can see to evaluate mileage. Even a single tank is not accurate enough because of the foaming present with diesel. I try not to fill too fast, but surely there are differences in fill ups due to foaming.
 

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I am not sure there are three numbers but will have a look tomorrow. (I thought the average shown on the instantaneous was the trip A number but sure don't know it for a fact.) I'll have to watch it for a while and see if it different.I am quite certain that tboth A and B reset their calculation periodically but do not know what the period is. The reason I feel confident about that is how rapidly the number changes with a change in driving style. I had my trip A not reset by me for 10,000 miles and it still changes relatively quickly when you do a bit of spirited driving. If it didn't reset and was really showing a 9900 mile average a few 0-60 full throttle runs wouldn't change the mileage but it does.
My Trip A has not been reset since my truck was built - the total miles match my odometer. I can tell you for certain that once I got past a few hundred miles, the Trip A average MPG never matched the overall MPG value.

With that said, the trip odometer also do not appear to give the MPG for the entire trip duration. Because if they did, that would mean that I was getting over 25 MPG in my nearly 1300 miles with the truck. Seeing as how the first few hundred miles (probably up until 300-400 miles) I was seeing MPGs in the 17-18 range, that would mean I have been getting mid to upper 20's for the last 900-1000 miles. While I have been doing more highway driving recently, it is certainly not driving that would be yielding 27+ MPG on a regular basis.

I suspect my next fillup with cause my Fuelly to show me at about 22-23 MPG overall, not at 24-25 as my Trip A readings indicate.

It would be nice to know how Ram/Chrysler's MPG calculations actually work.
 

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I guess I really dont understand the differences between instant, trip a and trip b. On my truck I reset trip a at each fill up, trip b has not been reset and on occasion I reset instant. I can tell you that trip a evic fuel mileage and my hand calculations have been spot on. I also understand my sample size of 2 fillups is quite small. In monitoring trip a's evic numbers it seems to keep an actual running total (mpg) and doesn't appear to reset after any mileage until I manually reset the numbers myself. After I reset trip a the mpg evic numbers change rapidly and as the mileage increases those numbers slow which is exactly as I would expect.
 

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image.jpg

Since my fuel mileage is so stinking low, the dealer did a 100 mile driving test & compared the EVIC reading to their hand calculated figure. So, for 100 miles, the EVIC was within .3 of a mpg of their hand calculated figure. The pic is what the tech wrote on my service ticket. I wouldn't say ALL our trucks are this acurate, but I'm positive that mine is pretty darn close to real. [insert fast talking DJ reading a disclainer]
 

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View attachment 6278

Since my fuel mileage is so stinking low, the dealer did a 100 mile driving test & compared the EVIC reading to their hand calculated figure. So, for 100 miles, the EVIC was within .3 of a mpg of their hand calculated figure. The pic is what the tech wrote on my service ticket. I wouldn't say ALL our trucks are this acurate, but I'm positive that mine is pretty darn close to real. [insert fast talking DJ reading a disclainer]
Man, I hope they get your truck sorted out for you, I'd be mad too if that's all I got. Best of luck.
 

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Man, I hope they get your truck sorted out for you, I'd be mad too if that's all I got. Best of luck.
Keep in mind that these figures are pulling our little 6' X 12' 1500 lb. trailer EMPTY. Without the trailer, it's 20-22 mpg - the same as a Hemi gets. I've talked to a few dealers about trading - they want to trade it at $20,000 less than new! I don't even have 10,000 miles yet. These trucks are not worth the extra $$ we paid for the diesel in my opinion. I'm going to wait a bit & lemon law it or it will blow up & it can be FCA's problem.
 

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Keep in mind that these figures are pulling our little 6' X 12' 1500 lb. trailer EMPTY. Without the trailer, it's 20-22 mpg - the same as a Hemi gets. I've talked to a few dealers about trading - they want to trade it at $20,000 less than new! I don't even have 10,000 miles yet. These trucks are not worth the extra $$ we paid for the diesel in my opinion. I'm going to wait a bit & lemon law it or it will blow up & it can be FCA's problem.
It's a matter of perspective.... I would've paid even more for the diesel. But mine works exactly as expected.
 

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Keep in mind that these figures are pulling our little 6' X 12' 1500 lb. trailer EMPTY. Without the trailer, it's 20-22 mpg - the same as a Hemi gets. I've talked to a few dealers about trading - they want to trade it at $20,000 less than new! I don't even have 10,000 miles yet. These trucks are not worth the extra $$ we paid for the diesel in my opinion. I'm going to wait a bit & lemon law it or it will blow up & it can be FCA's problem.

Ouch. I get better MPG's than this with crappy winter diesel and 0 degrees outside. I was still getting 23-24mpg. Now that it's warmed up, I'm back to 25mpg with winter diesel - and will probably get back to 26mpg ave once we're on summer fuel.
 

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You or your truck has serious issues Hershey. Either a heavy foot, high wind, or crap fuel.

I'm averaging 23-25MPG over full tanks (EVIC & hand calc almost always within .2MPG) with a 4x4, and still on winter fuel, and temps haven't been above 40 for a while (we're finally starting to warm up).

Just how fast are you driving to get such poor fuel economy? How much wind? How heavy is your foot on acceleration?

I've seen the difference 10MPH of wind makes; I've had 33MPG with no or a tail wind, and I've had 18MPG with a head wind or cross wind.
I've also had 4-5MPG change depending only on temperature (and subsequent idling).

I've got just over 100 idle hours, and just over 200 driving hours on the truck, and my fuel economy still greatly exceeds yours. Then again, my driving is about 75% freeway, at 72MPH.

I also get 13.4MPG towing my 7'x14' blunt nose tandem cargo trailer with about 4k pounds at 72MPH in 10 to -30F temps on a 850 mile trip snowmobiling. Instant MPG when going 55MPH was in the 17-19 range for the very short part of the trip where there was a 55MPH speed limit. That was with 10-15MPH head wind or cross wind the whole time; naturally, you can't go up to the cabin and not buck wind both ways... Murphy's Law.

To the OP, my EVIC is almost always underreporting the fuel economy, by about 0.2MPG on average.
 

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My EVIC seems pretty close to what aCar (Andriod app) is calculating. I have just less than 2000 miles on my 2015 Big Horn and here are my specs from filling up

February 26th- Filled up with 19.61 gallons, Average was 19.4 MPG
March 7th- Filled up with 19.66 gallons, Average was 16.3 MPG
March 15th-Filled up with 17.94 gallons-Average was 20.5 MPG
Haven't filled up this week yet but these are Fairbanks, AK Temps where it was -40 for a week or so, so there was a lot of Remote start, idling for several minutes plus winter blend.

My EVIC is showing about 22.4 which should be close since there are weeks where it's Highway to and from work (about 14 miles each way to base) and then going up large hills hunting for places to take pictures of the Aurora
 

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You or your truck has serious issues Hershey. Either a heavy foot, high wind, or crap fuel.

I'm averaging 23-25MPG over full tanks (EVIC & hand calc almost always within .2MPG) with a 4x4, and still on winter fuel, and temps haven't been above 40 for a while (we're finally starting to warm up).

Just how fast are you driving to get such poor fuel economy? How much wind? How heavy is your foot on acceleration?

I've seen the difference 10MPH of wind makes; I've had 33MPG with no or a tail wind, and I've had 18MPG with a head wind or cross wind.
I've also had 4-5MPG change depending only on temperature (and subsequent idling).

I've got just over 100 idle hours, and just over 200 driving hours on the truck, and my fuel economy still greatly exceeds yours. Then again, my driving is about 75% freeway, at 72MPH.

I also get 13.4MPG towing my 7'x14' blunt nose tandem cargo trailer with about 4k pounds at 72MPH in 10 to -30F temps on a 850 mile trip snowmobiling. Instant MPG when going 55MPH was in the 17-19 range for the very short part of the trip where there was a 55MPH speed limit. That was with 10-15MPH head wind or cross wind the whole time; naturally, you can't go up to the cabin and not buck wind both ways... Murphy's Law.

To the OP, my EVIC is almost always underreporting the fuel economy, by about 0.2MPG on average.
Try telling this to a Ram service department! I've had this piece of crap since Aug 2014 & it has NEVER gotten the advertised mpg. Obviously, it's not bad fuel nor my driving. Every service bay I've had it to has the same story: "we can't gaurantee your mileage" or "there are no codes, so everything is normal"...so what would you do differently?
 

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As most, the"disparity" is common both ways.

One thing helping me is I have an extra fuel tank in the bed. Often go over 1,000 miles on fill-ups. That seems to make my Evic close to the hand-calculated result
 

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There is NO device(s) to measure Volume (Gallon counter) With all HPCR the entire Injection system uses Fuel for cooling and lubrication, Ram would need to install 1 device to count the volume form tank then another for returning fuel and compare the difference, The system they use now is more accurate then ever before, its all cycle VS load VS RPM VS boost couple with duration and Pressure, I can't believe they get as close as EVIC vs HC. In some cases the EVIC MPG is LOM lie-o-meter. I use The EVIC just to compare it to My HC mileage and see how much the LOM is off.
 
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