I usually get around 13 mpg when pulling my 33ft,11000lb loaded, fifth wheel. That, of course, is on flat ground doing 60 with no headwind. My truck is a 2018 Ram 2500, diesel with a 373 axle rating. I recently bought a 26 ft. travel trailer, 5000lbs empty and here's my dilemma. I pulled it on mostly flat ground, no wind and maintained 60 mph and was only getting 11-12 mpg. What gives? I was thinking maybe frontal area, but the fifth wheel is two feet higher up front, so I'm not so sure that's the case. Some other coefficient mathematical formula is at play. The truck empty remains the same as far as mpg is concerned. Any thoughts?

Air flow. The fifth-wheel is closer to the truck and the air flow continues up over the front of it. The trailer being further back allows the airflow to wrap back in around the truck and hit the full frontal area of the trailer.

Exactly what Schelp said.I am glad you posted. This is interesting and I always wonder how much better mpg a 5th will get than a trailer for the stated reasons...Try to use some sort of wing air deflector on the tow vehicle. If you have a suv or a truck with a cap then the wing goes at the back and pushes air up and over the trailer/truck gap. This will help.I have a ghetto one on mine and by the bug splatter I can tell how high up the air is sent. It still hits the trailer but is not going into the space behind the truck and hitting the entire trailer.I plan to make a bigger wing to get the air all the way over.

You need a few more trips under your belt to see if it is related to what you are towing or just road/wind/temperature/fill conditions. A couple of friends of ours have 5th wheels, we have a regular trailer. All are similar weight/length, tow vehicles are from all 3, ford, dodge, gm. All are dieselsWhen we travel together and stop for fuel, seems like all of us are taking the same amount of fuel +/- a few gallons with typical fills in the 30 gallon range. And it varies as to who has used the most (or least) fuel.

If you just bought it, I’m guessing the outside temp is lower. Lower temps decrease fuel mileage!

I'm going with the air flow effect. A cap might solve some of the mpg issues, which is in the future plan. Temps were in the low 80's day time to 60 at night for West Texas and the first drive from the dealer was around eight hundred miles. 11+ was consistent for all refills.

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kellem
Explorer
Nov 02, 2021
dodge guy wrote:
If you just bought it, I’m guessing the outside temp is lower. Lower temps increase fuel mileage!

I believe it to be the opposite, better milage in warmer months. Imo
Grit_dog
Navigator
Nov 01, 2021
Not that it matters, but FWIW, unless you re-geared your truck, it has 3.42 gears. Only final drive ratio offered on srw Ram diesels from 2014-2018.
TurnThePage
Explorer
Nov 01, 2021
Last summer I took a couple kayaks on a camping trip for the first time. They were mounted on top of the truck cap. My mileage improved almost 2mpg. The cap itself affects mileage negligibly.
Road_Phantom
Explorer
Nov 01, 2021
I'm going with the air flow effect. A cap might solve some of the mpg issues, which is in the future plan. Temps were in the low 80's day time to 60 at night for West Texas and the first drive from the dealer was around eight hundred miles. 11+ was consistent for all refills.
dodge_guy
Explorer II
Nov 01, 2021
If you just bought it, I’m guessing the outside temp is lower. Lower temps decrease fuel mileage!
ktmrfs
Explorer II
Nov 01, 2021
You need a few more trips under your belt to see if it is related to what you are towing or just road/wind/temperature/fill conditions.

A couple of friends of ours have 5th wheels, we have a regular trailer. All are similar weight/length, tow vehicles are from all 3, ford, dodge, gm. All are diesels

When we travel together and stop for fuel, seems like all of us are taking the same amount of fuel +/- a few gallons with typical fills in the 30 gallon range.

And it varies as to who has used the most (or least) fuel.
ajriding
Explorer II
Nov 01, 2021
Exactly what Schelp said.

I am glad you posted. This is interesting and I always wonder how much better mpg a 5th will get than a trailer for the stated reasons...

Try to use some sort of wing air deflector on the tow vehicle. If you have a suv or a truck with a cap then the wing goes at the back and pushes air up and over the trailer/truck gap. This will help.

I have a ghetto one on mine and by the bug splatter I can tell how high up the air is sent. It still hits the trailer but is not going into the space behind the truck and hitting the entire trailer.
I plan to make a bigger wing to get the air all the way over.
schlep1967
Nomad
Nov 01, 2021
Air flow. The fifth-wheel is closer to the truck and the air flow continues up over the front of it. The trailer being further back allows the airflow to wrap back in around the truck and hit the full frontal area of the trailer.

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