As I stated in another post, after talking to a few guys I know that worked at NASA, and the horse trailer company, Brenderup, I came to the strange conclusion, after a couple dozen trips to Sunset Beach, that has changed the way I haul stuff to get the most out of the MPG of my truck.
All I have to do now is apply it to my Kite Trailer and go from 12mpg to about 20mpg.

As stated by Dino,(about his Cube) the roof racks reduce the aerodynamics of any vehicle that travels above 20mph.
I have an "03" Diesel, 4x4 Dodge Ram Quad Cab with a canopy and the typical Lumber Rack all Contractors have, and oversized mud/snow tires.
For the sake of discussion, I will state the freeway speed I travel is between 65 and 75.
With my truck completely empty, and set up as stated above, I get 22mpg at 65 and 18mpg at 75.
Now after removing the lumber rack, things changed to 28mpg at 65, and 25mpg at 75.
If I keep the rack off the truck and load it up with work tools, supplies, and garbage, to the point of filling up the back seat also, I will loose 1-2mpg at both speeds.
Now If I empty the truck and hook up the trailer,(7x14 enclosed tandem axle) my mpg goes to 12 and will not change no mater what. After a bazillion calls to the trailer company, Dodge, and all the trailer modification companies, I was pissed to say the least arg. Everyone I talked to said that the mileage of 12 is quite good for what I am doing.

OK, there has to be someone who can answer my question, WHY? I ran into a trailer company named Brenderup. They were able to answer the question. I was asked how fast I can run if I was chased by a Bear, OK this guy had to many drinks for lunch and as I told him thanks for his time, he laughed and asked me if I was pulling a parachute as the bear was chasing me, would it make any difference. At that point I had to ask what kind of liquid lunch he had and if it was the weekly special.
He chuckled and explained his question.

All trailers have a flat back door with the sides, roof, and floor creating a box. Boxes are NOT aerodynamic. So how do you make a box, aerodynamic? You have to make the box a parallelogram. In other words the bottom or top, has to project farther that the other 3 sides. The basic shape of the trailers create a Parachute effect behind the trailer, thus reducing the aerodynamics. You have to breakup the air or change its flow. With a short reference to the space shuttle and the little chute it has for braking. This is the idea behind their trailer, which they claim gets 2mpg+ better than others.

Now I have a couple of retired friends from NASA and they said the same thing but with a lot more words that are a bit like suprcalfragalisticexpealidosus. OK, now we are getting somewhere.
I sent them a pick of my buggy on the back of my truck and asked what can I do to get better MPG.
Now we are getting somewhere, time to think outside the trailer box. The trailer is a work in progress and not quite ready for the manufacturing debut.

This is what I found by talking and asking and by trying it out.

Remove any and all roof mounted stuff, racks, cargo boxes, buggies, and mother inlaws.
Keep your speed down as much as possible and with slow starts and long braking.
Now here is the one that is cool. The use of a buggy rack and the buggy on the back of my truck, increased my mileage by 4mpg at 75 to 29mpg, and only about 300lbs of kite stuff in the back. The buggy has the ability to break up the parachute effect off the back of the truck. I don't need to do 65 any more, I can set the cruise control and take a nap now knowing my MPG is more than OK with me. I know it is only saving me 30 minutes on the drive to Sunset, but I can be on the beach that much more.

There is a bit more to the figures, and all kite mobiles are different but the idea is still the same.

V Nose will help alot

http://wellscargo.com/wellscargo-trailers/auto-trailers/autosport-v-front/gallery/

I had an OLD square box van that I made into a camper years ago. It was awful on gas. I added a open top visor on the front and a spoiler on the back. This really did wonders for my mileage. So it still wouldn't go up big hills but it did good on the highway!!
The front visor caused a draft like in a chimney and drew the air up the flat front of the van, The rear spoiler caused a disturbance in the vacuum of the flat rear of the van.

After this all started I took the trailer back to the dealer I bought it from and complained that the trip to NABX just about put me in debt with the crappy mileage, his answer was to try out a trailer with that type of nose. Hooked it up, filled the tank and drove to Portland and back to Olympia, with the truck and trailer EMPTY. 210 miles and filled up the tank again, figured the mpg at 13.5. I was not impressed.

One of the things that kept bugging me with the trailer was the back door to the canopy would keep popping open and would not stay shut with out locking it. I found that if I put the bike rack on the back of the truck with both bikes, and connect the trailer, the bikes broke up the air between the truck and the trailer and I got better mpg.

Jeff you've got quite the gem of a truck to get that kind of mileage. I have several friends that have had that era Cummins and the best they ever got without a tailwind was 22 mpg. To get that mpg they were unloaded, and steady speed around 65 mph on flat land.

Quote:

Originally posted by BeamerBob Jeff you've got quite the gem of a truck to get that kind of mileage. I have several friends that have had that era Cummins and the best they ever got without a tailwind was 22 mpg. To get that mpg they were unloaded, and steady speed around 65 mph on flat land.

I heard a bunch of guys say the same thing. Infact, Dodge says the truck will in no way get anything better than 16.
Started to think outside the box years ago talking to an old timer who had the identical truck I did and he towed a 38' 5th wheel. he was getting 25mpg going from Seattle to Scottsdale, AZ twice a year. I told him he must have been forgetting the fuel on the way back for those figures. He said the key was to build the crap out of the engine and then stay off the peddle, racing the truck only emptys the tank. Hmmmmmm.
I added intake, exhaust, transmission shift kit, the Edge with attitude juice thingy, 50 over injectors, etc. I am running 689HP and a bit more in torque. (was kinda cool watching the truck in the shop on the dyno). Being able to burn off all 4 tires in 4x is nice for the show at the stop light, just need to stop at the next tire shop for another set of tires. $1900.00 for a set of tires doesn't help with the cost of fuel or the lousy gpm. So the need to find ways to get more for less.

Ok, I'll buy it with the performance mods. A high horsepower (diesel) running at low demand can get better mileage than stock. All your mods would contribute to mpg gains. I'm not sure I will bite on 25 mpg with a 38' camper though. Most would get 10-12 with that trailer. That much wind resistance and weight requires hp and hp requires fuel. I can see getting 2-4 better with mods but not double....on any vehicle.

A economy car with a teardrop trailer would do nice too. That's my plan. Make sure to add a transmission cooler to the car to protect the transmission from overheating u-haul can install them fairly cheap. Cooler and install for a ford escape is 140ish. That's the heavy duty one not the standard one.

My duramax is getting about 16 - 18 mpg empty and about 10 - 12 mpg with our 30 ft camper behind it. But I have a heavy right foot and not many beat me to the top of the hill even with the trailer in tow lol Nothing I love more than passing those mini vans and hybrids pulling that trailer blowing smoke on them

I guess I should put my buggy on the back so I can gain a few mpg. That sounds better than spending money on truck mods

That is some good lecture above ....
Now I understand what happened to my Audi ..... Normally I can get 27mpg average on highway ... Last snowkiting trip it did only 20mpg.... Was thinking that something is wrong with the car .... After reading you comments I realize that my roof rack with snowboards and skis may be to blame .... Unbelievable how much difference it makes ...

I leave my buggy rack on the back of my Durango all the time since I realized I was getting better mileage. one of my jobs requires me to drive 148 miles round trip and 2mpg makes a big difference. + I live in a small town and now that is how I am identified, the guy with the weird rack on the back.

I was getting the motorhome ready for a trip in a couple of weeks and took all the receipts/paper work into the office and got looking at the gas receipts. ARG.

Did a little calculating with the mileage, gas costs, log book and found when the buggies were on the back of the RV I got 9-10mpg instead of the regular 5.6mpg with the trailer. Then got to thinking about the trips with the bug and kites on the roof with the 2 bugs on the hitch mounted rack off the back end, the trips without any bugs or stuff outside the RV. I definitely need more driving time with the different scenarios to get a better idea of the mileage but it looks like the motorhome is not going to play the game as the truck has.

In a nut shell, looks like the best mpg (in all circumstances) is when I carry the bugs on the rack off the hitch, which is what I had hoped for. Nothing to be excited about, but better than nothing.
65 gallons of gas, at $3.45 per gallon, equals $224.25 to travel 464 miles without the trailer or buggies. Or 580 miles with the buggies on the back for the same cost.
Just wish I could find some way to convince the wife that we get better mileage with the bugs than without them.:D

Now if I could get all my stuff from the trailer and store it in the basement of the RV, I would have it made.:wee:

by no means are my results as well documented as jeffs, but as far as roof racks go my yakima rack/basket on the roof costs me 2-2.5 mpg. So smooth and bald my taco is getting 16-17 mpg and with the roof rack 14-15 add a couple of mtn bikes up top and your looking at 12 mpg. I am amazed at how poor my mileage is when compared to the rest of you

i'm going to try your theory out. I'm going 200 miles North this weekend. I'll put my rack on the back going up, then take it off coming back. F250 Diesel.

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Originally posted by BigMikesKites i'm going to try your theory out. I'm going 200 miles North this weekend. I'll put my rack on the back going up, then take it off coming back. F250 Diesel.

I have a canopy on my truck, if you do also it should work.
Just remember, going north is uphill and going south is downhill, you will definitely get better mpg's on the way back.

Yes, got a shell on the back. the rack won't stick over the top..

interesting fact; it is a myth that a truck with the tailgate down gets better mileage but on myth busters they proved to get better mileage with the gate up.

I have to say all this talk about buggy racks and mpg got me thinking about my solution. So I will share it with all of you.

The best way I found to improve my MPG on the Chevy S-10 I owned (4.0l V6 Vortec) coming back from NABX last year was to make Jeff haul my buggy back.

Saved me bank on gas.

Thanks Jeff

Quote:

Originally posted by MDK interesting fact; it is a myth that a truck with the tailgate down gets better mileage but on myth busters they proved to get better mileage with the gate up.

I saw where someone did a comparison on the tailgate issue and they found (in their test) that the best was tailgate down, worse was tailgate up, even worse was tailgate missing. Worst of all was one of those nets in place of the tailgate. YMMV

Quote:

Originally posted by BeamerBob Quote: Originally posted by MDK interesting fact; it is a myth that a truck with the tailgate down gets better mileage but on myth busters they proved to get better mileage with the gate up. I saw where someone did a comparison on the tailgate issue and they found (in their test) that the best was tailgate down, worse was tailgate up, even worse was tailgate missing. Worst of all was one of those nets in place of the tailgate. YMMV

interesting, the myth busters showed how with the tailgate up there is a ball of pressure in the bed making it more aerodynamic, which made sense, I'm sure we all have experience looking out the rear view and seeing a piece of trash floating around in that ball Bobby, maybe we are thinking of the same show and I may be remembering it wrong, oh well I don't have a P/U anymore anyway...traded it for a dump bed trailer

The test I'm referring to was before mythbusters. Just different test, different results.

Quote:

Originally posted by BeamerBob The test I'm referring to was before mythbusters. Just different test, different results.

yep YMMV

This did NOT work for me. I drove .... Well.. my 15 yo son drove to OKC to pick up a buggy today. We drove up without anything on the outside of F250 w/ a camper shell. 6.7 Diesel.
He got 18.9 mpg on the way up. We strapped the buggy on a VTT buggy hitch rack and started back with me at the wheel. After 40 miles of 14.4 mph we pulled over for lunch and tossed everything back in the back of the truck. 21.7 was my final the rest of the way in. The only other time i've seen 14.4 was dragging a 20 ft. flat nose trailer behind me. The wheel was above the roof line about 1/2 of the wheel.

Quote:

Originally posted by BigMikesKites This did NOT work for me. I drove .... Well.. my 15 yo son drove to OKC to pick up a buggy today. We drove up without anything on the outside of F250 w/ a camper shell. 6.7 Diesel. He got 18.9 mpg on the way up. We strapped the buggy on a VTT buggy hitch rack and started back with me at the wheel. After 40 miles of 14.4 mph we pulled over for lunch and tossed everything back in the back of the truck. 21.7 was my final the rest of the way in. The only other time i've seen 14.4 was dragging a 20 ft. flat nose trailer behind me. The wheel was above the roof line about 1/2 of the wheel.

Hmmmmm, Well let see.
Ford,
2 different drivers,
is your canopy height the same as the cab? Or is it higher at the rear? These 3 things are, well, uh, apples and oranges.
Sorry you didnt get what you were looking for. I've been working on this for quite a few years. One trip is not how I calculate things out.
I would guess your canopy is taller in the back than the front, that in itself changes a lot.
14 for half the trip back and total was 22 for the trip back? So why dont you tell me how you get such great mileage. You got me beat by a mile.

8.5mpg in our RV with nothing behind us and all the bugs in the basement..
8.5mpg with various stuff on a hitch mounted rack.
8.5mpg with a full size SUV in tow (empty or full, doesn't matter)
I guess it's just very hard to modify the aerodynamics of a 8.5' x 38' x 12.5' rolling box. Oh, and the 20,000lbs is probably a factor too.
We do get 1/4mpg better driving south than north and when Sue is driving vs me :o

I was at the RV show last week and seen a 2013 Entegra Cornerstone Coach.
I was intrigued with the back end that didn't look right and found out they had a problem for the last few years with the rear engine 600hp Diesel.
What the problem was with the earlier models was the engines had an overheating problem with the extra 150hp. The solution was to get more air to the rear engine compartment, and this was solved by building 2 ram air scoops on the roof that channeled the air along the roof edge to the back and down to the engine compartment. This posed another problem with the look of the scoops.
Now here is the cool part, they incorporated a spoiler into the design of the air scoops and the top of the rear. Similar to the air deflector of years gone by that were found on the back of some station wagons. With the change of the flat back the new Entegra has an out of the world bulge at the top of the rear end.
And with a big smile the salesman said it has increased the HP by 1-2% and the MPG 3-5%.
I have a problem with guys that wear to much perfume and look like they just got out of the tanning booth, telling me that this is just the coach I need. Dude the interior is nice but the basement sucks, there isn't enough room to carry 2 buggies and one set of kites if I chopped them up into tiny pieces to fill all the odd shaped non usable space on that stupid slide tray thing that has a 1" side that can only hold 100lbs. If it doesn't have a big, spacious basement, it is nothing more than an overpriced box. So when he said the design increased the mileage, I had to do some digging. Still digging, but the idea sounds good, will keep looking until I get in touch with someone at Entegra who really knows.

But back to the rear spoiler, thought that was an ingenious idea that will become more and more part of the newer coaches designs.
The other RV that was cool was the Outlaw toy hauler motorhome.

cab high all the way back. i'll get a picture soon

There is a company that makes an add-on product for your RV or trailer thats supposed to change the aerodynamics in order to improve fuel economy and improve handling. I know some people that added these to their RV and say that they got 1 to 2 miles per gallon better fuel economy and/or it improved the handling in strong winds.

http://www.airtab.com/gallery/rv.html

Darrin

Quote:

Originally posted by KitePwr There is a company that makes an add-on product for your RV or trailer thats supposed to change the aerodynamics in order to improve fuel economy and improve handling. I know some people that added these to their RV and say that they got 1 to 2 miles per gallon better fuel economy and/or it improved the handling in strong winds. http://www.airtab.com/gallery/rv.html Darrin

I looked into these some time ago. They were using them on boom box cars here, dont know why.
1-2mpg is nothing to throw away.

That is interesting and passes the first impression test. They might actually work. Not too expensive either. Well when I do the math, my camper would cost about $200. I don't tow it enough to pay that back even if it did return 2 mpg. Someone that puts in lots of miles might get a payback.