Abysmal fuel economy

[Leadfoot1776James]

18 5.7 392 gear I am at 17 mpg if I take it easy

 

[JoeCo]

I always run recommended octane in all my vehicles. I am fully aware of detonation and octane rating to match compression. I figure 89 was what the motor was engineered with so part of ownership. I know 87 is acceptable but I never know when I need to tow or haul a heavy load, so I want my motor running with fluids it’s spec’d for.

It’s not just for detonation, it’s also for optimal motor performance. My 2011 Taurus (NA 3.5) says min 87 but use higher octane for better performance. I can attest to the claim running tanks with 87,89, and 93 with a live data scanner showing big difference between 87 and 89. There was a marginal difference between 89 and 93, so I run 89. I haven’t had a chance to do the same with the Hemi.


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Are you planning on doing that test on the hemi? I'd be very interested to hear those results.

 

[runamuck]

I am at 12.5 mostly freeway driving around town and 8 towing my 6000# trailer. 5.7 with 3.92 rear end. my son has 2017 with same equipment and gets a steady 20 on the road and 16 around town. I too am starting to worry that something is wrong with ecm or motor.

 

[Kfield]

Are you planning on doing that test on the hemi? I'd be very interested to hear those results.

If I can get two weekends and if I can still access the tool I will.

I am at 12.5 mostly freeway driving around town and 8 towing my 6000# trailer. 5.7 with 3.92 rear end. my son has 2017 with same equipment and gets a steady 20 on the road and 16 around town. I too am starting to worry that something is wrong with ecm or motor.

Unhook your battery for 30min to an hour or over night. This will reset the learned data in the computers. After you have ran a day or two fill up and see if anything changes.



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[limited delmo]

I've got 1800 miles on my 4x4 non-etorque truck and it's averaging for the whole 1800 miles right at 19.0 on 87 octane. I have noticed losing about 1-1.5 mpg with certain gas stations. I'm guessing it's winter blend at these gas stations. Slightly disappointed I'm not in the 20's, but I didn't expect it and it's not a big deal.

For comparison my old trucks, a 2017 F150 3.5 ecoboost 4x4 got 20.5 mpg and a 2015 F150 2.7 ecoboost 4x2 got 24 mpg. I did drive an Etorque for a weekend and I'm pretty sure if I got that option I would easily be in the 20's and I might be slightly better than my 2017 F150, which is pretty impressive considering it's an old V8 that's just be slightly updated through the years.

 

[hksvr4]

My father in law has the 2018 Hemi and he said around 10-15k miles the mpg get better. Im at 1100 miles and 11.2mpg mixed. I would say 80% city and 20% highway.

 

[runamuck]

not starting out very good. the 2017 sierra 4x4 ccsb 5.3 v8 I traded in got 20+ on the highway right from the start and 9-10 towing the same trailer. granted my ram has a little larger motor plus 3.92 rear end vs 3.42 in the gmc, but the ram also has an 8 sp. tranny..and with more powerful motor I dont have my foot in it as much to get things going.

 

[adrianp89]

Just went up 6 PSI in each tires to 42... immediate results seem to show an increase, will report back after a few days.

 

[hksvr4]

Just went up 6 PSI in each tires to 42... immediate results seem to show an increase, will report back after a few days.

Although by increasing the tire pressure will stiffen up the ride and handle better, but will create abnormal tire wear.

 

[adrianp89]

Although by increasing the tire pressure will stiffen up the ride and handle better, but will create abnormal tire wear.

I ran this old set around 42 to as well and they looked new after 30k. I just noticed a few weeks ago I was at 35-36 and finally got time to get them back up.

 

[TommmyD]

Well the fuel economy seems to be improving. Up to about 16mpg. I am guessing the EPA rating is an across the board for all the models of 1500's. I am assuming the Rebel gets the worse being that it rides higher and the tires along with the lack of the aerodam in the front. If it can get at least 17 mpg average I'd be happy

 

[Kfield]

I’m getting ready to throw on a almost new set of 33’s falken wildpeak at3w’s off my old truck for winter. Looking to see what the E rated tires will do to the mpg.


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[adrianp89]

I’m getting ready to throw on a almost new set of 33’s falken wildpeak at3w’s off my old truck for winter. Looking to see what the E rated tires will do to the mpg.


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I am floating around 15-16 with 50/50 city highway with my G2s. As previously mentioned, I hope to see a bit better now that I upped my tire pressure. Doing first oil change soon as well.

 

[Kfield]

I am floating around 15-16 with 50/50 city highway with my G2s. As previously mentioned, I hope to see a bit better now that I upped my tire pressure. Doing first oil change soon as well.

I just broke 12k. My first one was at 900 and the factory fill still looked clean which was surprising. I cringed going over 1k, 2k, and 5k not changing oil. Figured I would follow factory recs. If it breaks it’s on them. Just seems odd during break in period going with a regular OCI.


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[Dannyb]

2019 limited, 5.7, 392. 3k miles, just drove from Tampa Florida to 90 miles north of Tuscaloosa Alabama, 800 mile trip one way, solid 21 mpg. 17.5 mpg combined prior to trip. I’m extremely happy with the performance and mpg. Now if FCA can just fix my 12.1 screen that’s been on the blink since they pushed an update. They know of the problem and are working on it.

 

[Max Limited]

During break-in I consistently got 19.5 MPG. Once I completed my break-in period, which for me was 1500 miles, my right foot went rogue and now my mileage has dropped to 17-17.5. Still very good but not as good as it could be. My rogue right foot is fully supported by both ears screaming, damn the gas mileage, full speed ahead! So I think it basically comes down to how you drive and why have a Hemi if you don't use it! Love that exhaust sound and will love it more once upgraded, just trying to decide which will give me great sound and no drone.

 

[slim chance]

last tank showed 19.2 on the computer and calculated to 18.8 ..... lots of local stop and go ... this is really a great truck to drive .... don't like the tail gate, set up for my travel trailer it is only a half inch from hitting the ball when tail gate is open!!!!!! the tail will open when hitched BUT the trailer coupler would hit the tail gate thus gotta watch the auto open button on the tail gate

 

[RAPOM 707]

During break-in I consistently got 19.5 MPG. Once I completed my break-in period, which for me was 1500 miles, my right foot went rogue and now my mileage has dropped to 17-17.5. Still very good but not as good as it could be. My rogue right foot is fully supported by both ears screaming, damn the gas mileage, full speed ahead! So I think it basically comes down to how you drive and why have a Hemi if you don't use it! Love that exhaust sound and will love it more once upgraded, just trying to decide which will give me great sound and no drone.

Borla or Corsa for sure. Those are a guarantee for no drone.

 

[OrganizedChaos]

Just another data point.

Last weekend did an 1600 mile round trip.
2019 Laramie Off-Road 3.92 5.7 - 2800 miles at end of trip
First leg no trailer speeds 70 - 90 (Texas, gotta love it) 18.6 mpg 89 octane
Second leg loaded tandem enclosed trailer acting as a sail speed 65 - 75 10.2 mpg 89 octane

After about 10,000 miles my 14 would do a bit over 20 on trips similar to the first leg of this trip.

 

[RoadRamblerNJ]

The recommended octane is 89 and 87 being acceptable. So your observation is no surprise. I just miss the days when all grades were separated by 10cents, and my leaded race fuel I thought was outrageous at $2.50 a gallon.


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Ahhh yes, the light purple Cam 2 fuel. Used to mix about 5 gals of that with 5 gals of Sunoco 260 leaded, play with the distributor a little and go to Wilson Ave & Ave P in Newark and street race.
And yeah, the price differences were minimal.