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Discussion Starter #1
2019 Ram 2500 crew cab short bed Laramie 6.7
Just completed a round trip drive from east coast to Arizona then down south to Georgia where I picked up a new trailer. then back north home.

no trailer out to Arizona or to Georgia.
averaged just about 21 mpg the whole way, 80-85 mph the whole way
could go about 600 miles per tank full.
picked up a 16x7 enclosed trailer
2700lbs empty. should be nothing for the 6.7 right?
averaged about 11mpg the whole way home Towing
half of what I did with no trailer. Barely made it 290miles per tank.
is this normal. ?
if so it’s pretty disappointing, and I’m scared to see what it will get towing my camper.
just over 6000 miles in 6 days.
was a fun road trip though.


thoughts ?
 

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In my opinion the biggest factors that hurt fuel mileage are speed and aerodynamics. I’m definitely not an engineer but if I recall correctly the drag coefficient increases exponentially with speed especially with poor aerodynamics. Basically the faster you go the greater the drag increases. Box sided trailers really drag hard at higher speeds which kills mileage...but when you have a lot of miles to go you tend to go faster particularly with a truck that tows very stable. I think you will find the fuel mileage is competitive with other big diesels towing the same loads. Honestly the best thing I’ve seen to increase fuel mileage is towing slower...but that involves patience I don’t always have. Anyway this is just my opinion on it.
 

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I have a 7x16 enclosed trailer and it returns abysmal towing mileage as well. It's like towing a giant billboard sideways.
 

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What speed where you going? Once you get over about 67mph in my rig mpg goes way down.
 

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I have a 7x16 enclosed trailer and it returns abysmal towing mileage as well. It's like towing a giant billboard sideways.
You should try my 8x16, which is also extra tall, and not a V-nose.

I'm generally going 75-80.
 

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Discussion Starter #8
I get the wind resistance, I do.
but still seems low to me for a diesel.
when I load it full of quads and stuff I should expect 9 mpg?

yes will it tow anything up a mountain but, still. My old 2012 hemi got 10 mpg towing a 20’ enclosed with a car in it.
 

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Wind resistance doesn't care about weight.
I get the wind resistance, I do.
but still seems low to me for a diesel.
when I load it full of quads and stuff I should expect 9 mpg?
In case you missed it the first time, weight isn't as much of an issue as wind resistance is.
Unless you're constantly starting from a dead stop, or always going uphill.
 

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Like others have said, wind resistance.

I can tow my dump trailer weighing in excess of 8k and get 12ish. I towed a single axle open trailer with a large expanded metal gate and side by side with a windshield/roof. Best I could get out of that was maybe 14 running 75ish.


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You should try my 8x16, which is also extra tall, and not a V-nose.

I'm generally going 75-80.
Mine is an extra tall, too.
 

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Mine is an extra tall, too.
It took me hundreds of gallons to figure it out, but after looking at all the bugs on the front of the wide and tall one I got a narrower, extra low V-nose. Basically the same width and height as the 2500, which had a a shell.
Huge difference in mileage.
 

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80-85 mph empty doesn't equal a legitimate 21mpg in any truck excpet maybe the baby diesel 1/2 tons unless you had a good tail wind driving west the whole way, maybe.
80-85 mph with a cargo trailer, 11mpg sounds about right to me. If you got 11mpg towing an empty 7 wide cargo trailer at, say, 70mph I'd say it was low by a couple mpgs.
 

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I pull a 40' 13k 5th wheel. 2,000+ mile round trip to Florida and back, I averaged around 10.4 MPG that was 95% highway running 60-70 MPH. That was hand calculated, not the dashboard computer. Most other trips come in around the same MPG, too.

As others have said, once you go over 70 mph, your mileage will plummet exponentially. Like fall off a cliff. One other important thing about towing at 70+ is that most trailer tires (unless otherwise stamped) are only rated to 65 MPH. So if you are pushing it hard, be sure to have good quality tires on the trailer otherwise mileage will be the least of you problems ;)
 

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In my opinion the biggest factors that hurt fuel mileage are speed and aerodynamics. I’m definitely not an engineer but if I recall correctly the drag coefficient increases exponentially with speed especially with poor aerodynamics. Basically the faster you go the greater the drag increases. Box sided trailers really drag hard at higher speeds which kills mileage...but when you have a lot of miles to go you tend to go faster particularly with a truck that tows very stable. I think you will find the fuel mileage is competitive with other big diesels towing the same loads. Honestly the best thing I’ve seen to increase fuel mileage is towing slower...but that involves patience I don’t always have. Anyway this is just my opinion on it.
We have never gone over 65 when towing, first what's the hurry and second do you know the towing speed for your truck and trailer tires speeding mph my trailer tires are lower then my truck tires and remember speed kills and mph goes down
 

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Going over 65, wind takes toll- over 2,000 rpms, engine speed will take a toll. Both and your wallet pays the price. Upside is you get to the next fuel stop quicker.
 

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Aero drag, thus power (and fuel) required increases proportionally with velocity squared. Towing at 80-85 is never going to get much mileage with any kind of box behind you. Even an empty flatbed has extra drag that will kick your fuel mileage in the ass if you drive that fast.
 

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....first what's the hurry...
The "hurry" is that if I drive 20% faster I will get there 20% sooner.
I'm sure it's different if retired or on vacation, but I want to get to the destination asap. Besides, my engine really likes 2,000 rpm, which puts me at right about 80 mph. Perfect, I think.
 
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