It has been the observation of many, since the FEH was first introduced, that rolling hills, or even mountains are very advantagous to high fuel economy.

Without breaking laws of physics, the downhill side tends to more than make up for the uphill side.

Example: 100 miles of flat at 60 MPH might net 40 MPG = 2.50 gallons used.

50 miles uphill typically nets 25 MPG. 2.00 gallons were used.*
50 miles downhill typically nets 125 MPG. 0.40 gallons were used.*

The round trip to the mountains used 0.10 gallons less.*

* Based on actual trip data in my 2005 FEH going up I70 west of Denver, and back down to Denver. Elevation change of more than 5000 feet in 50 miles.

 

Towing a U-Haul 4x8 Virginia to Wyoming.

Tank MPG Location of fill-up
1 21.9 Mint Spring, VA
2 23.9 Huntington, WV (partial fill) & Frankfort, Ky
3 24.9 Mt Vernon, IL (Partial fill) & St Louis, MO
4&5 22.6 Concordia, MO & Salina, KS
6 21.6 Colby, KS
7 22.6 Denver, CO
8 24.9 Laramie, WY
9 21.6 Rock Springs, WY
10 Final fill-up not done yet.
Partial fills had to do with gas prices, I follow prices and when I am in a high state I fill up just enough to get to a lower state.

I did not weigh this setup. The U-Haul 4x8 was rated at 700# EW by their website. What I had to carry was lightweight, an antique piece of furniture (Not particularly heavy) some electric trains, a box of lampshades, and some lamps. I also loaded stuff in the back of my FEH. So I believe I put no more than 300# in the trailer and probaby less.

Here's the placarded or manual numbers (for 4WD FEH):
GCWR 4980#
GVWR 4760#
Tongue load from trailer 1000#
I believe I was reasonably close to these limits without exceeding them.

This vehicle performed magnificently, acceleration was just fine, braking was fine. All elements of performance from the drivers seat tells me it is well "within the safety and endurance envelope."

I believe it is under-rated as a tow vehicle.

Having said that be aware if you overload a vehicle & trailer and happen be required to weigh in at a states weigh station, you can be fined and told to unload to limits before proceeding. So choose wisely.

I believe those sections of the mpg calcs that were so much better had to do with the aerodynamics of the tow & rolling terrain. Though mine wasn't necessarily good aerodynamically, it was cleaner than an open trailer with various shaped loads.

 

I do the same. I travel a lot and find MO and CO and WY to be some of the lowest cost gas. I find Nebr. to be one of the highest, and it is neighbors to the others. Go figure. I can bypass NE totally with my Insight, and almost not by gas in that state with my FEH.

Hey, you drove within 15 miles of my home! Coming back the same route?
I also collect trains of all sorts.

Tongue weight is the downward force of the trailer on the tow vehicle.
You came no where close to putting 1000# on the rear of the FEH.
In fact, could you lift the trailer "tongue" by hand? Probably. Likely, you had less than 100# on your FEH. A good rule of thumb is a 10:1 ratio.
Every 10 pounds of trailer, puts 1 pound on the tow vehicle.
I tow 3200 pounds, and only put about 320 on the rear of my FEH.

The FEH is rated so the tounge weight + interior cargo ( incl. passengers ) should not exceed 1000 pounds. I weigh in at 200#, thus when towing, I can still add 480 pounds of cargo or ~3 more passengers to the inside and still be within limits.

I would have to agree with that!

I have traveled to all the states* West of the Mississippi plus IL and IN and I have never seen a state were a private, non-commercial vehicle needed to be weighed. However, if you are grossly over loaded, and it is blatently obvious, I think any officer can write you a ticket on the spot without a weigh-in under a general clause of "unsafe operation".

Even with my "big white 7x12x9" at 3200 pounds, I'm no where close to this.


*Ops... I can't speak about WA or OR... guess I havn't been there... or Alaska,

 

I used the words "tongue load" instead of weight specifically because I was referring to the weight being pulled not the download on the tongue.

I've moved 19 times during active military duty, with the antiques my wife collected over the years I've pulled a U-Haul 6x12 many times with my Suburban. I got it on loading the trailer.

Maybe I should have used drawbar load. The FEH has a limit of 1000# for total trailer load as opposed to tongue weight. Don't confuse the download on the tongue with drawbar pull. The GCWR tells the story. The max total load the FEH is "allowed by Ford" to pull is the GCWR.

With regard to weigh stations for non-commercial haulage, I didn't say you had to stop for any of them. But you can be required to if, for some reason, they get interested in you. Sometimes states set up temporary weigh stations in odd places for one day and they weigh any "likely suspects (smile)" that go by. So my words were cautionary only.

A private car pulling a U-Haul, even an open one with a visible load, is just not likely to attract any attention at all since these guys are really only interested in loads that damage their roads.

Final overall mileage was 23.4 mpg for the 2200+ miles.

It was clear that the engine had to work and that, had I let the speed control function with out the downbumps & upbumps that rpm would have been higher and therefore gas mileage lower. But in the end acceleration was fine, braking was fine, and mileage was pretty good.

Photo attached... like I said the aerodynamics of a rounded brick...

 

Well there you have it.
You towed roughly one-third the weight as I did, in a trailer with probably one-half the frontal cross section. 23 MPG is totally on par. Mine is 7' wide x 9' tall x 12' long. ( length being least significant )

As a suggestion, perhaps you could proof-read your posts for clarity before hitting "submit"? We all know what we meant to say when we type, but sometimes we don't put down in black and white exactly what we meant to say. Then I need not correct "mistakes" that were not mistakes, just mis-prints.

Drawbar load is a good one, but one nearly impossible to know, being a dynamic value. At rest, the drawbar load is zero on level pavement.
A certain value at 10 MPH, and a totally different value at 55 MPH.
This value is greater on an incline, and less on a decline.
The drawbar load is never = to the trailer weight, as long as your tires are on the ground!
Tounge load, or tounge weight, is easy to measure, and fairly constant.
Total trailer weight, also pretty easy to figure, and what is used to determine GCWR is probably, in my opinion, the least valuable to know. ( as this thread illustrates ) GCWR = Gross Combined Weight Rating

While vehicle makers need to put something on paper ( I think just so you can compare vehicle A to vehicle B ) there is not one perfect, or maximum value for towing. So many variables go into play.

Tounge weight is important for suspension, tires, and handling properties.
Drawbar pull is important for engine power, and transmission capability.
Total weight of the trailer is least important... If my trailer was empty (1300#) and yours was loaded with bricks (2000# ) yours may still be easier for the FEH to tow due to shape. Mine has electric brakes, thus at 3200 pounds, mine is easier to stop than your 1000 pounds.

I hope this thread shows what is doable, and what can be safely done with the FEH.

 

Dare I say on further examination that the U-haul pictured was one-third the frontal area, ( of mine ) and completely within the aerodynamic "shadow" of the FEH? 23 MPG might be a tad lower than expected. I forget... is your AWD? Probably on par for AWD and 2 MPG lower than I'd expect from a FWD.

 

What is involved with installing brakes on a trailer that does not have them? How difficult would this job be?

 

I do proof read my stuff, not that I always get it right... I chose tongue load intentionally to differentiate it from tongue weight... On reflection I should have used "drawbar load."

Don't forget there is static loading and dynamic loading. There is a design maximum grade all of which figures into the GCWR.

Regarding frontal area: the aerodynamic flow over the top of the FEH results in a downturning of the air into the gap between the trailer and the FEH. This partly borne out by my experience with my Suburban.

With my Suburban and 6x12 U-Hauls I see that the actual load inside the trailer makes little difference in MPG. W/O trailer I get 15.5 on interstates and W/Trailer I get 11.5 but, though I am sure there is some difference due to empty versus loaded, it really doesn't seem to show empty versus loaded. Recently I towed a 5X8 U-Haul behind it and... voila... got 11.5 mpg. I attribute this to the major increase in aerodynamic load.

I think the bigger difference was the "cleanliness" of the load. Even though my 4x8 was smaller frontal area than yours, the open trailer and random arrangement of load makes for more interference aerodynamically and at highway speeds that makes a big difference (remember the equations are cubic - so doubling speed increases aerodrag by 8).

I really don't think there is the shadow you speak of. (Yes there is one, but the space between the FEH and trailer is so large that its of little advantage.)

Yes, mine is an AWD.

 

I agree the towbar on a U-Haul is exceptionally long... probably to reduce weight ( leverage ) and make it acceptible to more vehicles. Also, makes it easier for the human when connecting and disconnecting.

However, even at 10 feet back, the trailer is getting one helluva draft from the FEH at highway speeds. Not perfect, but significant.

And turbulent air produces less drag than still air... but it's mostly getting a draft benefit. The FEH gets a significant benefit ( like 15% ) 100 ft. behind a semi at 60 MPH.

 

Couldn't disagree more.

The downturn of airflow from the roof of the FEH occurs within a few feet. The FEH is so short that the air flows up and then back down in a relatively smooth and continuous curve. (Need to ensure you differentiate between skin friction and bulk flow of air here.)

This is noticeably different with an 18 wheeler. The truck & trailer combination is so long as to leave the airflow somewhat stable in a straight line when it passes over the back of the trailer. It then takes a bit longer to begin downflow.

It is true that turbulent flow has less drag than laminar flow, but I suspect that if you run the numbers you'll find that nearly everything you do with a car operates in the turbulent flow region. (I know what some car companies advertise with wind tunnel demos... but none of us drive in a wind tunnel.)

As I have mentioned from my towing experience with my Suburban, I believe the dominant resistance, at speed, is that of the impingement of the downflow from the FEH into the front of the trailer.