Your ACTUAL gas Mileage with a 5.7 Hemi

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boblonben

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Location
Texas
Ram Year
2017
Engine
Hemi 5.7
i bought a used 2014 1500 Big Horn with a 5.7 hemi and I use 87 octane gas in it. My dash computer shows the gas mileage as about 10% better than what I calculate when I divide my miles driven by the number of gallons burned. For example, my "Trip A" readout that was reset when I last filled the tank said I had averaged 19.6 MPG. My hand calculation for the same tank of gas showed that I averaged 17.6 MPG. This has been pretty consistent and the truck always reports better mileage than what I'm actually getting - never worse.

How accurate is your mileage calculator?
I have a 2017 and a 2022, boht 5.7 both driven just about the same as to use wise, some around town a bit on the highway, no towing this past month or so. I use onoly 8y7 octane. previous did test and saw I did better on it than 89. Anyway. My 2017 dash read out says 19.6, figure out by hand last fill up it was 19.2. The 19.6 is the average over 42K miles. My 2022 has 4126 miles on it, also only use 87. Last fill up it said 20.4, figured by hand it was 19.4. So yea the dahs gauge reds a bit high but not a lot really. I live in south central Texas, fairly flat roads and all, hot weather, so a/c on all the time, etc. Just saying......
 

boblonben

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Location
Texas
Ram Year
2017
Engine
Hemi 5.7
I have a 2017 and a 2022, boht 5.7 both driven just about the same as to use wise, some around town a bit on the highway, no towing this past month or so. I use onoly 8y7 octane. previous did test and saw I did better on it than 89. Anyway. My 2017 dash read out says 19.6, figure out by hand last fill up it was 19.2. The 19.6 is the average over 42K miles. My 2022 has 4126 miles on it, also only use 87. Last fill up it said 20.4, figured by hand it was 19.4. So yea the dahs gauge reds a bit high but not a lot really. I live in south central Texas, fairly flat roads and all, hot weather, so a/c on all the time, etc. Just saying......
Only difference between two truck is the 2017 has a 3.91 rear and the 2022 has a 3.21
 

VettDrAl

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Location
Woodinville
Ram Year
1500
Engine
Hemi 5.7
My computer mpg is also optimistic. Typically says I get 1 mpg better than I really do. 2019 Ram Big Horn 5.7 hemi. I get 15 mpg in town and 19-20 highway.
 

Carlo Santin

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Location
Ontario, Canada
Ram Year
2020
Engine
5.7 Hemi
I have a 2020 Big Horn with the off road package so I'm lifted 1". Falken Wildpeaks. In mixed highway and city driving I'm about 18mpg. City only I don't bother looking because it's horrible. Love my truck though so the gas mileage is a bit of an afterthought. I didn't buy it for the gas mileage.
 

ramphil09

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Florida
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2014
Engine
Cummins
Although I have a 2014 2500 diesel I get the same results. Computer reads about 20mpg but hand calculating says about 18mpg. 10% off.
 

brilliantnick

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Location
Washington
Ram Year
2021
Engine
5.7 hemi
Recently, I took a week long trip.
I drove for 39 hours idling for 1 hour +- whatever the calculator goes by.

During which I drove 2,109.4 mi
Burned 105 gallons of gas
Costing $459.31 averaging 20.1, mpg

5.7 w/ 3.92
Crew cab 6'4 4*4
Off-road package

It was the first long distance trip I've taken in the truck 'empty' That is to say everything that I was carrying with was inside the vehicle or underneath the tonneau cover.
 

farout75

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Location
Laurie, MO
Ram Year
2017
Engine
5.7 L
i bought a used 2014 1500 Big Horn with a 5.7 hemi and I use 87 octane gas in it. My dash computer shows the gas mileage as about 10% better than what I calculate when I divide my miles driven by the number of gallons burned. For example, my "Trip A" readout that was reset when I last filled the tank said I had averaged 19.6 MPG. My hand calculation for the same tank of gas showed that I averaged 17.6 MPG. This has been pretty consistent and the truck always reports better mileage than what I'm actually getting - never worse.

How accurate is your mileage calculator?
The computed in your truck measures the mpg that you are getting at the very time, not the total accumulated mpg. If on a long trip you will see it vary as you drive. My 17 1500 5.7 gets 17 to 21 depending on temp, wind, what I am carrying and so forth I have 113,600 miles on it..
 
Joined
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Location
Las Animas County Colorado
Ram Year
2018 Crew Cab 4x4 Big Horn
Engine
Hemi 5.7 V8
Best MPG from our 2018 RAM 1500 Crew Cab Big Horn AWD w/5.7 was highway driving from WA to UT (mostly scenic two lane 65-70 mph) first week of June this year. Observed 23.4 on Costco gas (85 to 87 octane). Just my wife and I and our luggage. About 9 month old OEM size Ironman All Country AT set at 41 psi.

Handy gizmo from Harbor Freight helped keep correct tire pressure (get the bigger battery for best performance):

 

Wanted33

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Location
Down South in Dixie
Ram Year
2022
Engine
5.7L
We just took a 1200 mile road trip. 500 up, 500 back, and a couple hundred around the countryside of the location we were visiting. The "lieometer" showed 22.8 mpgs on 87 octane. I tried to stay within 3/5 over the limit with the fastest speed limit being 70 mph. Now, I know that's too high (I think manufacturers do that to trick the average consumer) so I figured (in my old head) around 21, and a small amount of change just for kicks. I was quite happy. '22 Laramie 2wd Crew Cab 5.7L w/321 gears.

Heck, I would have been happy with 20 flat.......:)
 

ColesRAM

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NE FL
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2020
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5.7 V8
As I posted on another thread about mpg, I find this interesting to me as a new RAM 1500 owner. I have a stock 2020 Laramie 1500 CC, 5.7 HEMI etorque. Got it in July with a bit over 36K on the clock. Haven’t started a mileage log yet, (didn’t even drive it for a month, as we were out of the country) so have been using only the computer. With that, the computer shows 22-25 for highway/interstate driving and 17-19 around town. I find these numbers surprising good but suspicious to say the least. As I drive it more, the highway numbers have come down some to 20-22 and the town driving hold steady at around 18. I was burning 87 octane but now switched to 89. Hadn’t noticed any change in performance or mileage. My wife likes it a lot, so she drives it whenever she can. Bouncing between us two and our driving style effects the mpg, so I‘ll need to keep two logs. Bottom line, while this mileage discussion is interesting, I didn’t buy a truck for the gas mileage. That’s just a side benefit if it’s there at all. I still like this truck regardless of its gas mileage.
 

ram1500rsm

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Trabuco Canyon, CA
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I stopped checking MPG but whatever the dash says is more generous than the actual MPG when you do the basic math.
 

DILLIGAF

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My daughter's sh!tbox gets 45mpg. And I still have to do the coils and spark plugs :p

Did a 2 Hour data log on it today...


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Nurseman1313

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Denver
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2017
Engine
Hemi 5.7
I use 85 octane dealer said it was ok to use and I average 17.5 city and 21 mpg highway in my 2017 5.9 hemi and do not use eco setting
 

CAGEYAR

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Stockton, NJ
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2017
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5.7L HEMI
I don't drive for mileage.
I drive NJ to VA and back often. Sometime IL and back.
Most roads are 70 mph so I'm doing 75 mostly.
Hurts the mileage since at that speed you're pushing a big lump so I get 19.8 highway.
Around town is usually 17 or so. I'm good with that.
Best vehicle I've ever owned.
 

ram1500rsm

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Found some in my buil thread, This was back with KO2's in 37x12.5x17. 16mpg aint bad on 37's :)
1664128520609.png

I'm still on KO2's but back to 315/70/17 for a big while now. I'd think the truck should be around 18-19mpg, that is 91 octane without the DOD stuff. Now and again, what you see in the cluster is very generous on the RAM's. If you do your hand calculation MPG you'll easily observe around 2mpg LESS than what the cluster says so in reality my truck should be around 16-17mpg which it aint bad for a Hemi powered truck at almost 7lbs on 3.92's with 35's.

This is why we have a Kia Rio when we want to save gas and don't need the truck for daily duties. This is why i don't obsess with MPG anymore.
52365363989_1825dd82a4_h.jpg2022-09-17_04-55-29 by RAM RSM, on Flickr
 

JohnUSA

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Tacoma, Wa
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2009 Laramie
Engine
5.7 Hemi
2009 Laramie. The best I've gotten on the freeway, 70 mph, is 16mpg. Around town is 12mpg. I had a 2019 Rebel that did a little better, as I recall. MPG never entered into the buying decision either time.
 

CamperMike

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Peoria, IL
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Hemi 5.7
The engineers designed the "fuel computer" to purposely lie to give you that "feel good" feeling. Having driven several different makes and models, and done real mileage math versus "fuel computer" math, I have discovered one immutable truth: fuel computers lie.
My experience is that Mopar fuel computers lie. My Ford is very accurate as is the Mitsubishi we got for my son. My Ram, my old Town and Country van, and my wife's Pacifica all overestimate fuel mileage by over 5%.
 

Zaxxs

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Mine isPretty close, but I go by litres per 100km at 12.8 this trip. Is mpg based on US or imperial gallon since there's a fair difference between them? It's just over 18 miles per us gallon or just over 22 miles per imperial gallon.
I am an engineer who has spent a lot of time looking into these discrepancies between pumped fuel and dash MPG data in class 8 trucks (semis) . Your comment about metric Vs imperial reminded me that we found "rounding errors" between Metric and imperial, always in favor the truck showing better MPG than actual. When we used more digits in the conversion the numbers came out much closer to actual. I tend to believe the OEMs are know this issue exists, but like those better numbers showing up on their dash.
 
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