Fuel Mileage Gauge Inaccuracies

[spinxt]

So I’ve been watching the fuel economy gauge for a couple days and something seems “off”. It seems like the gauge is over estimating how much fuel is being used at idle. I first noticed when I spend a few days remote starting (and running for about 10 min). During those few days of doing that, my fuel economy went down to like 10mpg.

so the other day I ran a test. I reset the gauge and drove around town for about 10 miles. When I shut the truck off, my fuel economy read 13.8mpg.

The next day, I got in the truck and started it (I did not use remote start). As soon as the truck fired up, the fuel economy gauge was at 8.5mpg?

how did I loose 5+ MPG overnight when the truck did nothing but sit idle in the parking lot?

 

[kuba]

I've noticed this too.
But at the end of the day, my trip meter, which I typically reset at fill up, seems to show pretty accurate mpg compared to hand calculation.

I've noticed also that resetting one of the mpg meters resets them both. They might be a bit buggy.

 

[PorBoy]

Shucks I don’t even look at it anymore lol, I just fill up Monday/Wednesday/ & Friday. The guys at the service stations hate me .

 

[RunsWithBeer]

Hand calculating my mileage is consistently showing 1.1 to 1.5 MPG less than the EVIC measurement.

 

[JimD007]

I don't know how the software is programmed but the truck mileage is based upon fuel flow rate which results in significant limitations in the accuracy. I use the truck as a rough indication but I keep a little memo pad in the truck and write down the gallons and miles each fillup. From this I keep a spreadsheet of my mpg. Overall in >7500 miles I am just over 22mpg. But my truck has shown mileage higher and lower than this. It is some sort of rolling average displayed and I don't have a great idea of the interval. I know that on a trip of 100 miles or so, it seems to only include it's estimates from that trip - the mpg raises to where I would think it is on the highway. So it isn't a long term or even one tank average based upon my observations.

 

[RunsWithBeer]

I don't know how the software is programmed but the truck mileage is based upon fuel flow rate which results in significant limitations in the accuracy. I use the truck as a rough indication but I keep a little memo pad in the truck and write down the gallons and miles each fillup. From this I keep a spreadsheet of my mpg. Overall in >7500 miles I am just over 22mpg. But my truck has shown mileage higher and lower than this. It is some sort of rolling average displayed and I don't have a great idea of the interval. I know that on a trip of 100 miles or so, it seems to only include it's estimates from that trip - the mpg raises to where I would think it is on the highway. So it isn't a long term or even one tank average based upon my observations.

22 mpg, Wow!

I'd love to see 18 mpg average for one tank.

 

[Richard320]

I've been trying to figure out how they calculate that pretty much ever since I bought the thing. I know that when I reset everything to zero after a fillup, I can move the truck literally feet and see my mileage leap up to 12.5 or something, which is impossible, since half the time the engine was running since the reset it was in park. So it has some kind of memory. How far back that goes, and is it hours, miles, or days? That I have not been able to figure out.

 

[Amerinamese]

Hand calculating my mileage is consistently showing 1.1 to 1.5 MPG less than the EVIC measurement.

I just filled up today and I noticed the same thing. My truck said 18.3 MPG and I hand calculated to 17.3.

Sent from my SM-G986U using Tapatalk

 

[taz2016]

It's normal for almost all the vehicles I've ever owned. Out of dozens of vehicles of multiple brands, only one has been fairly accurate (early Acura TL). Every other vehicle computer has over calculated the mileage. My guess is the manufacturers do this on purpose to make the majority of owners - who don't hand calculate - feel better about the mileage they think they are getting.

 

[cochise111]

I just purchased a 2020 Laramie 4WD with the 5.7 L ETorque engine and the Offroad Package. It appears that the mileage calculator calculates zero MPG while idling, so it really hits your mileage. My 2017 Honda Ridgeline did the same thing. I had it for four years. Love my Ram, BTW. The mileage isn't great, but not much worse than the Ridgeline. For LEDs, the reverse lights aren't very good, especially when viewed through the backup camera at night. My RL appeared to almost have "night vision". I can live with it, though, and so far I like everything else about the Ram better than the Honda.

 

[Jako]

I just purchased a 2020 Laramie 4WD with the 5.7 L ETorque engine and the Offroad Package. It appears that the mileage calculator calculates zero MPG while idling, so it really hits your mileage. My 2017 Honda Ridgeline did the same thing. I had it for four years. Love my Ram, BTW. The mileage isn't great, but not much worse than the Ridgeline. For LEDs, the reverse lights aren't very good, especially when viewed through the backup camera at night. My RL appeared to almost have "night vision". I can live with it, though, and so far I like everything else about the Ram better than the Honda.

Many have added reverse lights, plenty of options.

Search results for query: reverse light compilation

5thgenrams.com

 

[Neurobit]

I’ve been using Fuelly for about eight years. Same routine every time. Fill up until it clicks. Reset odometer.

I do find that my gauge is pretty accurate. Sometimes is off by 1 MPG or so, but most of the time around .05. I can live with that.

 

[Dusty1948]

Of the three Ram 1500s I've owned, my current DT computer appears to deliver the most accurate MPG readings. To-date the deviation from hand calculated to the EVIC reading is 0.10% lifetime (see attached).

Note that the negative expressed figures in the EVIC column mean that the EVIC expressed a MPG number that was better than the hand calculated. Figures in the EVIC column that are not negative mean the EVIC underestimated the actual MPG.

Lifetime MPG average is 19.69.

Regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33 gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 03 June 2018. Now at: 041868 miles.

 

[PowerJrod]

Mpg at idle isn't valid. The computer calculates mpg based on RPMs, flow rates, etc...
I've found my current mpg while driving to be about 1.5 above what it actually is, which isn't bad compared to other vehicles I've owned. I drive about 22 miles one way 5 days per week...I fill up once every week and a half.

 

[cochise111]

Many have added reverse lights, plenty of options.

Search results for query: reverse light compilation

5thgenrams.com

Thank you. It just so happens that I have been looking for some auxiliary backup lights.

 

[Drewster]

So I’ve been watching the fuel economy gauge for a couple days and something seems “off”. It seems like the gauge is over estimating how much fuel is being used at idle. I first noticed when I spend a few days remote starting (and running for about 10 min). During those few days of doing that, my fuel economy went down to like 10mpg.

so the other day I ran a test. I reset the gauge and drove around town for about 10 miles. When I shut the truck off, my fuel economy read 13.8mpg.

The next day, I got in the truck and started it (I did not use remote start). As soon as the truck fired up, the fuel economy gauge was at 8.5mpg?

how did I loose 5+ MPG overnight when the truck did nothing but sit idle in the parking lot?

If you haven't noticed a theme yet, the cluster is probably *under* estimating that fuel usage. Port-injected V8's use a lot of fuel at idle, and putting on 0 miles at a stop means your average is going to plummet. This is why a lot of folks are excited about e-Torque - compared to my last Hemi, e-Torque averages 4-5 more MPG on the same stop and go commute.