2500HD gas mileage

Ray Pickle · July 15, 2022

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.

Flatus · July 16, 2022

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.

sheath · July 20, 2022

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?

Flatus · July 20, 2022

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.

sheath · July 21, 2022

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:

Flatus · July 21, 2022

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.

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

Flatus · July 21, 2022

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

sheath · July 22, 2022

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.

22z712500 · July 22, 2022

I get around 11 pulling my 4500 lb travel trailer.

Flatus · July 22, 2022

I will be doing the same trip on Labor Day weekend for college football game so will see how it goes on that trip.

Ray Pickle · July 25, 2022

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?

sheath · July 25, 2022

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

Another JR · July 25, 2022

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.

Flatus · July 25, 2022

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.

Ray Pickle · July 27, 2022

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!