Bad fuel mileage 5.7 hemi

[silver billet]

one thing I’ve noticed that will kill your mileage is cruise control, it’s fine for flat ground but through rolling hills it will destroy your mpg figures as it goes 75% throttle up small hills trying to maintain a certain speed constantly. As where manually you can just bleed off 3mph and stay in overdrive and keep the mpg up.

while this happens in most vehicles, it’s really noticeable on this ram. The instant mpg will drop to like 6 while it goes wild on the throttle

I noticed that too in my previous cars; setting cruise control to try and max MPG is a wasted effort. The best MPG comes from a light-and-steady right foot. As soon as you reach any sort of incline, the cruise control will quickly kick in the gas in an effort to maintain speed. But you should just use your foot, keep the gas steady (if possible) and let the truck coast up the hill (accepting that you might lose some speed, but will gain it again on the other side); or if you need to, slowly apply pressure, the slower the better.

As soon as I see a reviewer using CC for testing MPG, it's game over; they don't know what they're doing, unless they're in "flatville" and it's 0 degrees incline for their entire trip.

Course, you could argue, should a truck be rated with "real world usage" which would probably include CC? I suppose, but keep in mind that CC will decrease your max MPG if you're using it.

 

[SilverSurfer15]

I had mine disconnected for awhile, like 2 hours? And nothing happened.

But I left it unplugged over night once and everything happened. Started truck, radio was all jacked up. But after I drove the truck a bit, restated it, it all came back to normal.

Don’t know what it means but it happened.

 

[slimchance]

one thing i have noticed in this thread ... none of you have details of your trucks listed in your signatures, so it is kinda like comparing apples to oranges .... and i do not find the same results with the CC, IF the cruse control is OFF you still want to maintain your speed so you must push harder on the go pedal to go up hills and let off the pedal when going down the hills .... in PA this is something we learn early ...

 

[SilverSurfer15]

lol at PA comment. Well good for you then.

There’s also no way a hemi truck averages 18mpg in PA, not traveling through said hills. It will barely do that on the flat coast. So how do you have two fuelly signatures with 18 averages?

And 18 with a TRAILER in PA!?

 

[19reb]

one thing i have noticed in this thread ... none of you have details of your trucks listed in your signatures, so it is kinda like comparing apples to oranges .... and i do not find the same results with the CC, IF the cruse control is OFF you still want to maintain your speed so you must push harder on the go pedal to go up hills and let off the pedal when going down the hills .... in PA this is something we learn early ...

Apples to oranges? Right. Because my 5.7l Hemi and 8HP75 transmission is sooooo much different than your 5.7l Hemi and 8HP75 transmission.

I also find it hard to believe you are getting basically the exact same 18mpg in 2 different Rams with 2 different drivers. Also while pulling a trailer in city traffic? Really? BS!

My username is 19reb. It shouldn't be too darn difficult to figure out what vehicle I own and drive.

 

[SilverSurfer15]

Well I do think he had a point somewhat, in that some trims like a rebel just won’t get the mileage as a base truck with the extra rolling resistance.

I noticed he has quad cabs not crew, probably good for a 1/2 to 1mpg there. I just assume everyone has a crew but I guess that’s a bad assumption.

18 in PA still seems far fetched. 18 with a trailer is fake news for sure, but we don’t know far he went with it. Says short trips.

The only way this is even close to possible is never going through the hills on the highway and never going over like 60mph.

FWIW, my EB averaged like 13 heading up to Hershey through the mountains, and like 17 ish on some of the more civilized parts heading to NY. This all in the 70-75 mph range. Can’t imagine how bad a hemi would be in the Hershey section, you might be able to see the gauge move lol

 

[19reb]

My Rebel is a quad cab. Minus his e-crap, there is no difference. Except I don't drive in PA traffic. I drive in Clarksville TN traffic. Which is a pretty major difference. Yet I can't even manage 13mpg and this guy claims he is getting 18 in 2 different trucks with 2 different drivers while pulling a trailer. I call BS...

I do understand the rolling resistance and giving excessive acceleration to keep at speed up hills. My Rebel dips down below 5mpg current if I even think about putting pressure on the gas pedal and on flat land. So 18mpg in my situation is an impossibility.

Seems like this guy might be that dude who rides in the passing lane driving 40mph in a 55mph zone holding up traffic during rush hour....

 

[silver billet]

One variable not mentioned often, is; is this hand calculated or computer calculated? TFLTruck has shown time and again with their 2019 Rebel that the computer is inaccurate and often shows higher MPG than it actually is.

 

[cdancidhe]

My 2019 longhorn (1200 miles on it), 4x2, Hemi, short box, 3.21 gears, is giving me about 17mpg (as per computer) with a city/hwy mix (although hwy with bad often traffic). It went down to 15 when I did some trailering (about 5000lb boat/trailer). I just resetted the computer yesterday and did some city/hwy. I am around 16-17mpg. But I am trying to get those mpg up, so going light foot and I do use the CC.

Once I refill the gas next weekend I will know for sure how much I am getting. In the past; with other vehicles, the computer always gave me higher numbers than reality.

 

[Neokane]

My observation in my crew cab rebel no etorque is city seems to give the best mpg. Lots of eco/mds mode, Highway is pretty decent, and then interstate sucks...

 

[redbranch]

I'm averaging 17.8 mpg just daily driving, which is 80% country roads and 20% in town. Yesterday I did the first real road trip with the truck. Zeroed out the mpg at the beginning. The trip was 420 miles. 165 miles was interstate and the rest was county highways and back roads, with maybe 25 miles of city driving. I drove about 3-5 over the speed limit much of the time, and when I could, on the interstate I set the adaptive cruise and drafted behind semis for probably two thirds of the interstate part, which was 1/3 flat and 2/3 hills. My average mpg came out to 19.6. I'm pretty happy with that.

 

[RedRocketZ28]

My truck computer is usually within a few tenths of the Fuelly/Hand Calculated numbers. I have driven extremely easy with mine on this tank and the truck is showing 16.0 MPG. This is the highest I have seen it since owning it and I have 3/8 of a tank left. Most of this was highway/interstate with speeds ranging from 55-70.

Towing a little over 4,000 lbs. netted me in the mid 10's. Pulling my open car trailer empty, which weighs right at 1,800 lbs. got me about 12.5 according to the truck. That was running 75-80 though with a pretty decent crosswind. I fully anticipate being in the 9 MPG range when I start towing our 26' boat though. I also run between 70-80 whenever towing something.

My truck currently has 4600 miles on it and it's finally getting warmer here in Iowa. I am hoping I see a decent improvement in MPG still but I won't hold my breath. I would love to get the 18-20 MPG interstate numbers some are getting though.

 

[Gman]

Etorque is supposed to help out with this but I only hear complaints about the bad gas milage. I"m wondering if anyone with etorque are getting above 20 mpg on long interstate trips.

I run down highway 85 and I-25 to Colorado Springs and back and get 21.8 MPG. Just drove up to Steamboat Springs and back over the weekend. That's the stretch used by TFL Truck's Ike Challenge and included a couple of days of in-town driving and a quick drive up to Craig, CO and back. I got 20.8 MPG for the entire trip. I was hustling, used cruise control more than usual, and was not focused on max MPG.

I did notice MDS coming on while in the 70s. I've seen MDS engage more often as I log some mileage.

I love driving my truck. It's so comfortable on the road.

 

[slimchance]

IF you click on my /or wife's Fuelly average it will take you to our data ... then you can see the mileages for each fill up and see it is now 18.6 for my trk ... also, i normally run 5 over posted speed limits ... the short trips averaged about 100 miles in that fuel fill up .. and i live in souther lancaster co., pa ... in the "river hills", you are either going up or down hardly ever flat, no big cities and mostly "local" driving but fuelly does not account for this type of driving .... these numbers are ALL Fuelly/Hand Calculated ... since you all drive the same trucks, you know after a fill up the dash evic shows the expected "range" based on the last tank calculation ... see the last "range " in this pix .....

 

[slimchance]

lol at PA comment. Well good for you then.

There’s also no way a hemi truck averages 18mpg in PA, not traveling through said hills. It will barely do that on the flat coast. So how do you have two fuelly signatures with 18 averages?

And 18 with a TRAILER in PA!?

sorry this does not match your view of things but there are the facts ..... i have 2 utility trls, one is a 1500# gross aluminum trl and the other is a 7000# gross utility trl and of course a 7700# TT (have not pulled it yet but expect 10 mpg when pull it) ... maybe IF i showed you the licence plates and you did a google map of lancaster co you could believe i live in pa in the river hills .... sorry you guys get so upset that you can not get better mpg out of your trks ... here is some more fuel for your fire ... the last 2 tanks on "my trk" netted over 20 mpg hand calculated with the 392 rear and running E 15 fuel

 

[SilverSurfer15]

I’m actually not upset about my mileage, I don’t care that much or I would have made a different life choice.

Now you are saying that higher ethanol blends are yielding MORE MPG?

 

[machz]

Now that the weather is a little warmer low 40's at night and upper 50's during the day my MPG is going up. My last couple of tanks I have taken the exact routes to work and tried to drive the same way. I have filled with 87 and averaged 17.4 hand calculated for the first tank then I used 89 and got 17.3 hand calculated. So far I'm still happy with the MPG considering the gears and tires on this truck.

One thing that makes a big difference is anticipating a stop and letting off the gas to slow before the stop instead of running right up to the stop and using brakes. My wife does not watch traffic ahead as well and will run right up to a red light then brake. I see a light ready to change or see traffic slowing ahead and I let off the gas and coast. I get at least 1 + MPG better if not more than she does in my truck and in her car. The ECO light is on often for me and almost never for her.

 

[Goodkind's Dharans]

Anyone else getting less than 14mpg? My 4th gen got way better economy. I know it’s a truck and I don’t expect amazing economy, but i do expect to get what I got out of my 4th gen which was 16-17, and also does anyone have a vibration coming from the drivetrain when In 4wd hi or auto?

I am getting 13-14 combined. I was surprised by this because I have conservative driving habits (I'm older) and because the new HD trucks under full load are getting 12mpg. I do not agree with the folks who suggest trucks should get poor mileage.. well, just because they are trucks. In the past, I have never gotten less than the EPA ratings. I usually pride myself in squeezing 10% over the ratings. I should add that I am using mid-grade fuel.

 

[Jbird]

How would one go about resetting the PCM on these trucks? Pull the negative cable for 20 minutes or so?

Pull negative cable and press in brak

How would one go about resetting the PCM on these trucks? Pull the negative cable for 20 minutes or so?

Yep

 

[Neokane]

Pull negative cable and press in brak

Yep

And does this actually do anything other than reset the pcm?
I cant imagine this improves fuel efficiency.