Travel trailer "vs" fith wheel --MPG to tow

[soje]

How much difference in fuel MPG`S have you had with a bumper pull compared to the large wind resistance of a fiver?
I have noticed a high fuel consumption in a head wind.
Is it streamlining or lack there of that is to blame?
Feel like I am pulling a 13 ft high box at times.
I see trucks with all sorts of streamlining on the road.
JUST CURIOUS-not that I want a travel trailer/bumper pull unit.

[soje]

Thanks for all the great thought provoking responses. I still don`t know if the issue has been "put to bed" yet.
That Cumming MPG post is really good. Wind resistance/turbulance is not our friend.
Happy travels/happy trails to you--SOJOE

[Campinfan]

amxpress wrote:
I actually get better MPG towing my Columbus fiver than I did my 26' Jayco TT.
I'm sure aerodynamics plays the biggest part. Towing the Jayco TT was like pulling a big square box down the road. This is with my 6.7 CTD.

Me too. I went up from 7-8 to 8-9 mpg. 1 mpg doesn't sound like much but it is at least a 12% improvement. That means $100 of towing with the travel trailer now costs $88.00.

[mtofell1]

Rancher Will wrote:
.
However, most have told me that when comparing the two of approximately equal size the 5th Wheel RV permits a little better MPG, perhaps one to three MPG compared to a TT of the same size.

1-3 MPG is hardly "little better" when it comes to fuel usage, especially for someone who is talking commercial basis. Truckers and trucking companies can save thousands by just a fraction of 1 MPG.

I think anyone reporting more than about .5 MPG with the same weight 5th and TT is either suffering from confirmation bias or there are other factors they aren't accounting for or aware of (wind, terrain, etc.).

[laknox]

otrfun wrote:

laknox wrote:

CampingN.C. wrote:
This is similar to an episode of Mythbusters years ago where they tested the theory of a trucks tailgate being down increased mileage. The myth was busted as the truck with the tailgate up had much better mpg.

I can't find the video on the net but I remember them doing test in wind tunnels and it clearly showed the difference.

Somewhat off topic but still interesting.

Interestingly, the best mileage I've ever seen in my D'max was on a trip to CO several years ago, with a 14 cu ft chest freezer in the back, right up against the cab. I saw 23+ mpg while running 75 after DW told me that my fuel-saving 65 was too slow. 🙂 Surprised hell out of me, that's for sure. Simply =has= to be aerodynamics.

Lyle

23 MPG at 75 MPH is pretty darn good. Very possible it was due to aerodyanmics. However, depending on your route, it's possible elevation could have played a role, too. For instance, Phoenix is about 1,000 ft. lower in elevation than Tucson. I get 18-19 MPG with my Cummins, Tucson to Phoenix, and 16-17 MPG, Phoenix to Tucson.

Chandler to Cortez CO, via Gallup and Farmington; back via 4 Corners. Averaged about 22 for the entire trip. Normal highway, non-towing, is about 20-21...even with a clean K&N filter. I =did= use Diesel Kleen for the whole trip, so that may have helped a bit, too.

Lyle

[otrfun]

laknox wrote:

CampingN.C. wrote:
This is similar to an episode of Mythbusters years ago where they tested the theory of a trucks tailgate being down increased mileage. The myth was busted as the truck with the tailgate up had much better mpg.

I can't find the video on the net but I remember them doing test in wind tunnels and it clearly showed the difference.

Somewhat off topic but still interesting.

Interestingly, the best mileage I've ever seen in my D'max was on a trip to CO several years ago, with a 14 cu ft chest freezer in the back, right up against the cab. I saw 23+ mpg while running 75 after DW told me that my fuel-saving 65 was too slow. 🙂 Surprised hell out of me, that's for sure. Simply =has= to be aerodynamics.

Lyle

23 MPG at 75 MPH is pretty darn good. Very possible it was due to aerodyanmics. However, depending on your route, it's possible elevation could have played a role, too. For instance, Phoenix is about 1,000 ft. lower in elevation than Tucson. I get 18-19 MPG with my Cummins, Tucson to Phoenix, and 16-17 MPG, Phoenix to Tucson.

[laknox]

CampingN.C. wrote:
This is similar to an episode of Mythbusters years ago where they tested the theory of a trucks tailgate being down increased mileage. The myth was busted as the truck with the tailgate up had much better mpg.

I can't find the video on the net but I remember them doing test in wind tunnels and it clearly showed the difference.

Somewhat off topic but still interesting.

Interestingly, the best mileage I've ever seen in my D'max was on a trip to CO several years ago, with a 14 cu ft chest freezer in the back, right up against the cab. I saw 23+ mpg while running 75 after DW told me that my fuel-saving 65 was too slow. 🙂 Surprised hell out of me, that's for sure. Simply =has= to be aerodynamics.

Lyle

[bid_time]

It's all speculation and conjecture without the proofs. But if it makes you feel better thinking you're getting better fuel mileage than a similar TT, then go with it. Up until the proof one way or the other comes out you're allowed to believe anything you want. For me, the mpg's are not in the equation of what RV I want.

[CampingN_C_]

This is similar to an episode of Mythbusters years ago where they tested the theory of a trucks tailgate being down increased mileage. The myth was busted as the truck with the tailgate up had much better mpg.

I can't find the video on the net but I remember them doing test in wind tunnels and it clearly showed the difference.

Somewhat off topic but still interesting.

[otrfun]

Bumpyroad wrote:
did you have a cab high cap when you pulled a TT?
bumpy

No cap.

[Me_Again]

I went from a 9k square corner 5th wheel to a 12k 5th wheel with front and rear and mileage increased a little bit.

Hard square corners hurt mileage.

All the new 5th wheels going rear capless will get sightly less mileage vs ones with rear caps with soft corners angled in.

[neil57]

Nobody has mentioned wind direction or speed, that plays a big part in fuel economy. A cross wind will effect a TT much more than a FW because of the 2 separate profiles. My economy changes drastically with wind.

[StirCrazy]

my experience was similar to a couple. towing the old travel trailer (29 foot, 7500 lbs) with my 99 7.3I got about 11.4 mpg. same truck on month later with a new 38 foot 5th 11500 lbs I got 15.7 mpg. exact same trip route.

as mentioned the more aero dynamic front end of the 5th and being closer to the truck cab makes only one drag zone instead of two with the typical travel trailer.

steve

[laknox]

N-Trouble wrote:
Dont assume just because its taller a 5er has more air resistance than a TT.

5er and TV act like a single large mass cutting through the air while TT and TV act like two separate masses with a lot of dirty air in between.

^^^This...

Also, turbulence in the truck bed can hurt you, as well as rear-end turbulence. While a v-gate might not gain you in mileage down the road, it =can= reduce in-bed turbulence which, IMO, likely helps mileage a touch. I know it sure helps keep stuff in the bed!

A FW (or TT) with a rounded rear cap is also likely to get a touch better mileage again, due to reduced turbulence.

Rooftop wings likely do very little simply because the vast majority of RVers don't drive 100k+ miles a year to make the expense worthwhile. Same with skirting.

As an aside, I'd love to see a wind tunnel test on a FW with a light tubular frame on the roof that would support a cover for cleaning up the roofline while towing.

Lyle

[Rancher_Will]

We have always owned and pulled 5th Wheel RVS. However, over the years, usually at truck stops, I make a point of visiting with any commercial drivers who deliver RV's to dealers from the factories. Those drivers tow hundreds of all types of RV's and are very willing to give their impressions, advice and experiences.

There have been times when we visited about MPG towing various RV's. My experience over the years is that most of the commercial drivers believe that there is little difference in MPG between pulling 5th Wheel RV's compared to TT RV's. However, most have told me that when comparing the two of approximately equal size the 5th Wheel RV permits a little better MPG, perhaps one to three MPG compared to a TT of the same size. They also say that the shape of the front of the RV affects the MPG on any RV that they pull. Some have said that the smaller TT RVs usually have a flat front and even those smaller ones require more fuel per mile than most 5th Wheel RV's that have a more rounded front.