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2500HD gas mileage


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I have only had Big Red for about three weeks.  My commute is 46 miles one way and I usually set the cruise between 60-62 mph where the speed limit is 50-55mph.  There are a couple of hills where it will downshift to fifth gear and mostly flat terrain.  According to my Trip B, I have been averaging 17.2 mpg.  The 50 mile instant varies between 16 to 17.8 mpg.

 

After I put gas in her, I will get a better idea.  

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I also changed tires when I bought the truck. Didn't think it would matter but after reading some other forums, many have said that an all-terrain tire will lower your gas milage. By how much do you think if this is true??? Anyways I have some BFG all terrain KO2 LT285/65 R20. I also have a K&N intake, mainly for the sound (I enjoy the growl) and while K&N states you would gain MPG's other have said that it would actually lower them? More than likely I think the issue is the Driver. While I drive within the posted speed limits, I may be a little heavy on the throttle approaching said limits. Yay for gas prices!!!!! 

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I'm still all over the place fuel mileage wise, but seems to be averaging in the 14-s to 15s unloaded.

The DIC showed over 18mpg last night, but it calculates off the last 50 miles, not the entire tank.  Had just under 500 miles of driving yesterday from about 5,000' asl to over 10,000' asl, twice (round trip over a mountain pass in Northwest NM to Southwest CO).  I'm betting when the truck is filled up and hand calculated it will still be in that 14-15mpg range again.  lol

 

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Do not trust the computer to give you an precise accounting of your mileage.  Hand calculation is the only way to precisely know your mileage.  The computer can vary wildly.  The diesel high country on my last trip of 3957 miles the computer showed 15 mpg, trip average, but the actual mileage was 13

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9 hours ago, sheath said:

I'm still all over the place fuel mileage wise, but seems to be averaging in the 14-s to 15s unloaded.

The DIC showed over 18mpg last night, but it calculates off the last 50 miles, not the entire tank.  Had just under 500 miles of driving yesterday from about 5,000' asl to over 10,000' asl, twice (round trip over a mountain pass in Northwest NM to Southwest CO).  I'm betting when the truck is filled up and hand calculated it will still be in that 14-15mpg range again.  lol

 

I’m not saying anything about its accuracy, but FYI the trip pages show avg mileage over the trip from the last trip reset. 

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12 hours ago, Another JR said:

I’m not saying anything about its accuracy, but FYI the trip pages show avg mileage over the trip from the last trip reset. 

Thanks for the correction.  For some reason I was under the impression it calculated based on the most current 50 miles.  Which has been a bug in my ear, as it seemed stupid.

Now I know where the stupidity really lies... 🤔 

🤣

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3 hours ago, sheath said:

Thanks for the correction.  For some reason I was under the impression it calculated based on the most current 50 miles.  Which has been a bug in my ear, as it seemed stupid.

Now I know where the stupidity really lies... 🤔 

🤣

I think what you said about a 50 miles running average was correct for the DIC page you were describing, which is the fuel efficiency page, but I was pointing out the two trip pages also have a mpg indication for the miles since the last trip reset. 

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Put in just over 24 gallons of Shell 87 tonight...had just over 1/4 tank left and hand calculation revealed 15.69 mpg.  I almost had a heart attack when I paid $125!!!

 

DIC trip A gave me 16.0 mpg.

 

Actually better gas mileage than my old '08 Tundra!

 

Still loving this truck!

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Thats sound about right for DIC accuracy. I consistently see .3 mpg lower hand calculated vs DIC. Although it varies. Just to add to the mpg discussion I average 16.5 on the highway I have done better than 17 and as bad as 15.5..weather-terrain dependant. In town 12 is pretty typical. I typically run about 60 hwy 40 town per tank and hit mid 14s most tanks.

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  • 3 weeks later...

Just did a 3 plus hour highway drive with my 3500 hd gas with a Four Wheel Campers pop up slide in camper from Clallam Bay, WA, to Seattle, WA, which is sea level to sea level with a bunch of up and down 500 foot climbs, and the trip computer said 15.5 mpg at the end. Averaged around 65 mph. That’s my best yet with the camper!  

Edited by Another JR
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My truck has a bit under 10,000 miles now.  I've not noticed improved economy after the break-in.  Seems the best fuel mileage I see is traveling in that 55mph-65mph range over long distances.

 

Here is what the Owner's Manual (page 228) says about break-in:

"New Vehicle Break-In
Caution
The vehicle does not need an elaborate
break-in. But it will perform better in the
long run if you follow these guidelines:
. Do not drive at any one constant
speed, fast or slow, for the first
800 km (500 mi). Do not make
full-throttle starts. Avoid downshifting
to brake or slow the vehicle.
. Avoid making hard stops for the first
300 km (200 mi) or so. During this
time the new brake linings are not yet
(Continued)
Caution (Continued)
broken in. Hard stops with new linings
can mean premature wear and earlier
replacement. Follow this breaking-in
guideline every time you get new
brake linings.
. Do not tow a trailer during break-in.
See Trailer Towing 0 279 for the trailer
towing capabilities of the vehicle and
more information.
Following break-in, engine speed and load
can be gradually increased.
On new vehicles, the various mechanical and
electrical systems experience a “break-in”
period during the first 6,400 km
(4,000 miles) of routine driving. As the
vehicle is driven, the mechanical systems
adjust to provide optimal fuel economy and
transmission shift performance.
Electrical systems will adapt and calibrate
during the break-in period. A one-time
occurrence of clicks and similar vehicle
noises is normal during this process.
Normal driving charges the vehicle’s battery
to achieve the best operation of the vehicle,
including fuel economy."

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