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Discussion Starter · #1 ·
On the DIC, my combined mpg for my entire driving of 3300 miles is estimated at 33mpg. However, I downloaded and synced my cruze to the Onstar Remotelink app and there my mileage was at 37 mpg. So my question is, which one is more accurate?

I have also use 100 gal gas, so I'm guessing the DIC estimate is closer.
 

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Most on here see a few mpg less than the DIC on actual pump fill ups. However I have found the lower my MPG is this winter with more idling & cold starts the more accurate it is. For me my average is between 2-4mpg higher in the DIC than actual pump MPG.

Twice when I filled up a fully warmed up car & drove ramp to ramp on the interstate with the cruise set at 65mph I have actually got better than the cars DIC has indicated. In both those instances the car was 1/2-1mpg higher than the DIC indicated.
 

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Mines pretty accurate, always been within 1 MPG of the calculations for the most part. But I know quite a few people aren't happy with it.
 

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I have always been in the 1 mpg off range in the past. I was planning on posting again to see what people were seeing in the winter. My last 5 fill-ups in MN have either been spot-on, or the DIC is saying I got about a half mpg worse than hand calculated. My DIC has seemed to become even more accurate. It almost never over estimates the mpg, anymore.
 

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Remotelink will only pull I think the "Trip A" data from your DIC. So if you've just reset the MPG readout and not the trip data, it will show the whole current trip data which is probably for the life of the car so far. Actually, it shows both Trip A and lifetime, but Trip A can be changed. I've left my Trip B alone so I have average speed and mileage stats calculated over the life of the car.

Since Remotelink doesn't show tenths, it rounds up/down to the nearest whole number. So 33.6 will show as 34 in Remotelink.

As Erik said, mine is also generally between 3 and 7% high over calculated pump numbers depending on conditions. I've seen as low as 0 and 1% on highway only trips, but it's rare.
 

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DFCO isn't the problem. GM's method for estimating fuel consumption has been optimistic since at least the 2002 model year, well before DFCO technology was developed. My Montana's DIC was always 10% optimistic. My ECO's DIC is 5-10% optimistic depending on how much start/stop driving I do.
 

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Mine is off 2-4 mpg and I think this is due to the fact that I fill up with more fuel than the dic says I used every time.
I noticed the same thing. I reset my fuel usage at each fillup. If the computer says I used 12.2 gals since the last fillup, the pump will put in 12.7 gal. This type of spread has been consistent each time. The ECM calculates fuel usage based on fuel injector timing and flow rate calculations. However, the EVAP system is capturing fuel vapor and burning it through the intake system so the ECM doesn't have a way to account for that usage. A half a gallon burned as EVAP vapor in a 400+ mile tank of gas seems reasonable to me. That is why I think the actual usage is usually higher than what the computer thinks it used. If the fuel usage is low, the calculated MPG will be higher that actual.
 

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Yes. The DIC is accurate. It undercuts total MPG, however because DFCO screws it up somehow. On road trips the DIC is always within 2% of pump value.. sometimes over sometimes under.
This may be because of my theory mentioned above about the EVAP burn. The quicker the fuel is used by the car, the less EVAP vapor will be generated. This will allow the DIC fuel usage to be closer to actual. If it takes someone two weeks to use a tank of gas, there is more vapor trapped over time and burned unaccounted for by the ECM.
 

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Discussion Starter · #13 ·
Thanks for the replies guys. I think I am going to start counting at the pump to see the exact mileage. Could anyone tell me how to count the mileage if I put in 9.6 gal instead of the 10gal because I usually fill up on gas before it reaches E?
 

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Don't use the DIC's gallon reading. Use the miles driven either from the main odometer or a trip odometer. My preference is the main odometer because you'll never forget to reset it. Also, get a fuelly account to help you track your fuel usage.
 

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My DIC is probly bout 7% high on mpg also. Sure wish it was closer but I guess a person gets used to it.
 

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Re DIC, depends upon where & how you drive.

On Hwy driving steady my DIC is spot on, very close.
Back woods 2-lane roads with lots of DIC instant 99mpg, less so.

A few 50+ mpg tanks have been 3 mpg ~ optomistic on the DIC
I have over 25k mi and it is getting closer.
Display device Electronics Text Technology Electronic device

This tank actual was 12.2 gl. & 53.3 mpg

Please note the five tanks I've exceeded 50mpg were under optimal conditions.
I could have never gotten that if:
1. Traffic did not allow, I do not hold up other drivers.
2. My route was devoid of major hills.
3. The road surface is not "high drag"
4. If I did not have high t/p
5. If I did not monitor the DIC's mpg constantly.

Hard, maddening and tiring work.!
 

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That 10% may depend on the car. My 2013 Cruze ECO is almost exactly 10% over for every fill up over 13300 miles (47 fill ups). My wife's 2003 Venture used to average 0% difference (+/- 1% for each individual fill up) until about 2 years ago when the gas gauge started messing up and the computer numbers are no longer accurate. My 2010 Traverse did not have the DIC, so that was entirely manual calculation.
 

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I use fuelly to track my mileage. It is mathematically accurate and because it computes mpg over the duration of the mileage and fuel used, any effects from getting a few less tenths of a gallon in on a fillup are mitigated. Having said that, i do note was the DIC says when I fill up. Sometimes it is close, other times optimistic by 5% or so.

My trip 2 readout has run since the car was born. 12,420 miles and 41.4 mpg. Remotelink reports 12,420 miles and 43 mpg lifetime. 40.6 is what fuelly says...
 
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