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2500HD gas mileage


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On 7/13/2022 at 5:57 PM, Flatus said:

I pulled a 5300 lb travel trailer about 600 miles the last few days. Only 8.5 mpg's for me. I never ran over 65 mph.

Kinda disappointing.

Was that stop and go in town for a significant % of the tow? Possibly high headwinds or front quartering winds? That is low mpg for what you are pulling if your speeds are 65 or less. I average that pulling a 12k 13.5 ft tall fiver in the west and a little over 9 in the midwest. I acknowlege a fiver has better aerodynamics than a travel trailer but your shorter length, less height, and weight should more than make up for that.

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8 hours ago, Ray Pickle said:

Was that stop and go in town for a significant % of the tow? Possibly high headwinds or front quartering winds? That is low mpg for what you are pulling if your speeds are 65 or less. I average that pulling a 12k 13.5 ft tall fiver in the west and a little over 9 in the midwest. I acknowlege a fiver has better aerodynamics than a travel trailer but your shorter length, less height, and weight should more than make up for that.

90-95% highway. Light winds. Coastal Mississippi to Northern Mississippi and back. Rolling hills but definitely not mountainous. 

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On 7/15/2022 at 6:52 PM, Flatus said:

90-95% highway. Light winds. Coastal Mississippi to Northern Mississippi and back. Rolling hills but definitely not mountainous. 

I would have expected better mileage as well, especially since your truck is 2WD.  Like in the 9+mpg range.  

Wonder if you got a bad tank of gas?   Are you normally getting in the 14+mpg when not towing?

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3 hours ago, sheath said:

I would have expected better mileage as well, especially since your truck is 2WD.  Like in the 9+mpg range.  

Wonder if you got a bad tank of gas?   Are you normally getting in the 14+mpg when not towing?

I get 12-13 mpg in my everyday driving. My normal daily drives are a lot of 15mph- 45mph roads with plenty of stop signs and red lights though. I have not been on any road trips without towing something. About a month ago I drove to a lake in Alabama while towing a 16ft skiff with tiller motor. Truck had 3 people and bed was loaded with coolers and few other things.  I got 15 mpg on that trip. I always hand calculate my mpg because computer is always optimistic.

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23 hours ago, Flatus said:

I get 12-13 mpg in my everyday driving. My normal daily drives are a lot of 15mph- 45mph roads with plenty of stop signs and red lights though. I have not been on any road trips without towing something. About a month ago I drove to a lake in Alabama while towing a 16ft skiff with tiller motor. Truck had 3 people and bed was loaded with coolers and few other things.  I got 15 mpg on that trip. I always hand calculate my mpg because computer is always optimistic.

Yeah, it sounds like normally your truck does pretty good.  Hopefully the tow down south was just a bad tank of gas, that doesn't repeat. :cheers:

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55 minutes ago, sheath said:

Yeah, it sounds like normally your truck does pretty good.  Hopefully the tow down south was just a bad tank of gas, that doesn't repeat. :cheers:

That trip was 2 different tanks of gas from 2 different Chevron gas stations. Same results on both.

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20 hours ago, Flatus said:

^ The 8.5 mpg trip pulling the camper was 2 different tanks of gas from 2 different Chevrons is what I mean.

Pretty strange indeed. i have no idea why that happened to you.  With the crazy price of gas I sure hope it doesn't happen again.

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Is your truck pulling in 5th and occassionaly in 6th gear on flats to 2% grades? If not something isn't right. Do you lock out top 2 gears and pull in 4th to keep revs up? If so that would account for poor mpg. Iam at a loss otherwise for poor towi ng mpg. I can maintain speed on level ground up to 2% grades in most instances in wither 6th or 5th gear. Rarely do I downshift to 4th and rev to 3k range unless terrain is more hilly or headwinds. Check trailer brake adjustment, tire pressures on both?

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Remember the old days when trucks got 10 mpg uphill, downhill, towing 10 bazillion pounds, or free falling off a cliff?  lol 

I've noticed this truck has fuel mileage that ranges all over the place.  The most consistent fuel mileage is when towing the 14,600lbs 5th wheel.  It will either be approximately 8.5 mpg on the flats, or approximately 7.5mpg through the mountains.   Unloaded in town and on the interstates with 75-80mph speed limits drops mileage into the high 13 to mid 14 range.  Long back road trips will be high 15 to low 17mpg.

 

I've not had a truck before with fuel mileage this variable.  This is also the first HD gas engine truck I've owned that would run through a full tank at over 15mpg.  Since it runs on 87 Octane that is a double bonus.

 

All the driving represented in the below spreadsheet is at a conservative acceleration rate with speeds at or below the posted limit or basic speed law (lower of the two).  Cruise control use is maximized (I'm too lazy to push a gas pedal when I can push buttons on a steering wheel... lol).  The rows below with mpg in the 9-13 range is a combination of towing and unloaded.

 

One other note: mileage is hand calculated.  But I don't top off, and this is over many different fuel pumps.  So I'd guess there could be up to a 0.3-ish mpg variance due to this.

 

Date Mileage Fuel / Maintenance 20   Mileage
02/28/22 371 Fuel     14.19
03/01/22 821 Fuel     15.60
03/18/22 1126 Fuel     12.75
03/31/22 1115 Month end     14.18
04/02/22 1517 Fuel     13.02
04/03/22 1738 Fuel     7.42
04/03/22 1974 Fuel Partial fill 16.952 gls   N/A
04/03/22 2053 Fuel Final fill 19.882 gls   8.55
04/09/22 2398 Fuel Partial fill 17.2446   N/A
04/11/22 2488 Fuel Final fill 15.960   13.10
04/26/22 2767 Fuel Partial fill 23.152   N/A
04/27/22 2966 Fuel Final Fill 16.466   12.07
04/28/22 3221 Fuel     15.47
  2095 Month end     11.60
05/06/22 3509 Fuel Partial fill 23.325gls   N/A
05/08/22 3551 Fuel Final fill 9.831gls   9.96
05/09/22 3847 Fuel Partial fill 30.308gls   N/A
05/10/22 4018 Fuel Final fill 20.061gls   9.27
05/10/22 4224 Fuel     8.15
05/15/22 4632 Fuel Partial fill 15.682 gls   N/A
05/17/22 4785 Fuel Final Fill 24.261 gls   14.05
05/22/22 5154 Fuel Partial Fill 15.309gls   N/A
05/22/22 5154 Fuel Final Fill 8.132   15.74
05/22/22 5154 Engine Oil Top off engine oil w/5-30   N/A
05/23/22 5284 Fuel     7.71
05/24/22 5490 Fuel     8.67
05/30/22 5901 Fuel     15.91
  2680 Month End     11.18
06/01/22 6073 Fuel     14.49
06/01/22 6261 Fuel     9.04
06/02/22 6517 Fuel Partial Fill 18.754 Gal   N/A
06/03/22 6553 Fuel Final fill 14.659 gal   8.74
06/07/22 7027 Fuel 29.054 gals   16.31
06/08/22 7368 Service First Oil Change   N/A
06/09/22 7416 Fuel Partial fill 18.004 gals   N/A
06/12/22 7516 Fuel Final Fill 11.960   16.32
06/18/22 7966 Fuel     16.43
06/20/22 8356 Fuel     13.90
06/23/22 8422 Service Tire Rotation    
06/28/22 8729 Fuel     11.91
06/29/22 9145 Fuel     17.28
  3244 Month End     11.31
07/03/22 9586 Fuel     16.52
07/11/22 9860 Fuel     15.03
07/11/22 10243 Fuel     17.09
07/11/22 10599 Fuel Partial Fill 15.499 gals   NA
07/13/22 10627 Fuel Final Fill 7.489 gals   16.70
07/15/22 10803 Fuel     15.84
07/16/22 11193 Fuel     17.21
07/16/22 11693 Fuel Partial Fill 28.852 gals   NA
07/17/22 11889 Fuel Partial Fill 16.669 gals   NA
07/17/22 12170 Fuel Partial Filll 5.099   NA
07/18/22 12410 Fuel Final Fill 31.577 gals   14.81
07/19/22 12731 Fuel     14.34
07/21/22 13111 Fuel     15.98

 

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Maybe the OP could post a picture of the truck and trailer combination. Maybe he has a very high aerodynamic drag configuration - like a bumper pull trailer with large frontal area and an open truck bed.  

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3 hours ago, Ray Pickle said:

Is your truck pulling in 5th and occassionaly in 6th gear on flats to 2% grades? If not something isn't right. Do you lock out top 2 gears and pull in 4th to keep revs up? If so that would account for poor mpg. Iam at a loss otherwise for poor towi ng mpg. I can maintain speed on level ground up to 2% grades in most instances in wither 6th or 5th gear. Rarely do I downshift to 4th and rev to 3k range unless terrain is more hilly or headwinds. Check trailer brake adjustment, tire pressures on both?

My truck pulls anywhere from 4-6 gears. It will hit the 3000-3200 rpm range occasionally. I do not lock out any of the gears. I do put it in Tow/Haul mode every time I tow the camper though. Maybe I should try a tow without doing that. My trailer only weighs about 5200-5400 lbs loaded which technically is below the threshold that I should be using Tow/Haul according to owners manual. I keep up with my tire pressures regularly, including the camper. I actually use a TST pressure/temp monitor for camper tires. As far as grades go, I have no idea what percentage grades/hills I go up and down on. 

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On 7/25/2022 at 6:59 PM, Flatus said:

My truck pulls anywhere from 4-6 gears. It will hit the 3000-3200 rpm range occasionally. I do not lock out any of the gears. I do put it in Tow/Haul mode every time I tow the camper though. Maybe I should try a tow without doing that. My trailer only weighs about 5200-5400 lbs loaded which technically is below the threshold that I should be using Tow/Haul according to owners manual. I keep up with my tire pressures regularly, including the camper. I actually use a TST pressure/temp monitor for camper tires. As far as grades go, I have no idea what percentage grades/hills I go up and down on. 

I agree to consider non- tow haul at your weight the truck will pull in 6th gear far more often which may improve your mpg.  I would be curious of your results, please let us know if you try it. I'm such a frugal bastard I will turn tow-haul off whenever conditions allow to maximize mpg with a 12k fiver! Any sustained downhill grades or hills that it can safely be executed, or on level ground- slight inclines with a tailwind!

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