Offroad trailer Vs Roof tent MPG

[MOAK]

fuel mileage

I have been having this debate with myself for years now and finally built a small light trailer, more for the convenience, than anything. It cannot possibly hurt the mileage. With the Kanga Pack up top, we may as well have just set a square sail up there, so it is nice to have everything in easy reach. And yes, I built my trailer for less than 1500 bucks. E-bay, used parts from fellow jeepers, free access to scrap diamond plate & 1/4" 7075, friends with welders, and my own labor kept the cost way down. Our last trip, with the sail up top, we managed 16.5 mpg, over 2800 miles. I'll post up what we get going to mob and back, 6000 plus miles. Happy May to all!!

 

[ddog45]

one more heep over the hill

I will be driving over vail pass today pulling the chaser. I am using TheMike's scangauge so I to can figure out what it costs me to go play. Im planning on getting 12 miles to the gallon. I will report back in a week or so.:smiley_drive:

 

[alfio]

I have been having this debate with myself for years now and finally built a small light trailer

got a build thread? more pics? thanks

 

[AlexJet]

What is the size of RTTs packed?

 

[Mike S]

Like many things there is no absolute answer to the question that the original poster asked. This is a conversation that I have frequently with customers and prospective customers. here is what I have learned from customers and from my own experiences.

1. Trailers are great for hauling gear, but the extra weight is still being pulled by the same drivetrain. Lighter is better and an RTT on the trailer will probably have less MPG penalty than the same tent on the roof. There are pluses and minuses to both approaches.

2. What vehicle you drive will make a difference. The MPG penalty will be magnified with a low powered, lightweight vehicle. If you have a more powerful vehicle, the percentage of penalty will be less. Aerodynamics matter as well. I have a couple of customers who own older style Jeep Cherokees that SWEAR that they get better mileage with a tent (Maggiolina) on the roof that with the roof naked. Has to do with the Maggiolina 'filling' the space above the roof and eliminating back eddy drag. For most vehicles the penalty for an RTT n the roof will be from .5 to 4 MPG.

3. The SHAPE of the tent matters a lot. Fold up fabric tents (including our fabric tents) have a large, flat frontal profile. This really is a mileage killer at anything approaching freeway speeds. It's just physics at work. A streamlined tent will have much less MPG penalty.

4. Weight of the RTT matters. I have found that people routinely exceed the rated total load capacity of their vehicles. Four adults and a couple hundred pounds of gear, food, water, and fuel will quickly overload a small SUV and the bigger the vehicle, the more we want to stuff into it. Look it up for yourself. MPG and performance penalties mount up quickly with too much 'stuff'.

When Roseann contacted me about a tent for her FJ60 she was trying to attain a high mileage goal (30 MPG IIRC). The sleek and lightweight Columbus Carbon Fiber weighs only 73 lbs and that is what she got. She would have to say whether she reach her mileage goal with the diesel, transmission and other mods she made. I think she got close.

 

[Ford Prefect]

Yeah, $1500 to build a trailer raised my eyebrows too. I guess it could be done, but you'd have to be REALLY good with "recycling" things.

If you look around you can always find a free boat trailer somewhere. That is what I did. Picked up one out of the local dump, and then a little cutting and welding and I have a trailer for free. Now I will take it and add some queen size bed frame parts to make the sides (weld them on) and I can also use parts of that to make rails across the top. (about 10 bucks for the bed frame)

So once I get into the actual design of the trailer it will be the only money I actually spend on the thing. Oh, and I might add a nice axle to it. The one on there is fine, but I want a bigger weight capacity for when I use it for utility purposes, and my tires are a little small for my tastes. I also added a tool box for a side mount truck bed, which has given me a lot of space to store things until I put on drawers and such.

Again, I am into this one that I have about $30 including supplies, and then I put in another $100 for new tires when I got it (because the old ones were only 8" and were dry rotten.

Anyhow, the most important thing is the frame, that is where you spend the money, and I got mine for nothing... So yeah, you can make a pretty spiffy trailer for not much if you look out and have the time. (I have had the thing for almost two years, and I just tinker with it when I feel like it, or when parts come available for free... )

 

[rosalka09]

I think it depends where you want to go. If you pack up every day, rooftop is really your only option. Offroad trailer is more off road friendly than caravan. An offroad trailer is the best for me, but it does have consumption impacts.

 

[Hilldweller]

I lose about 5 mpg with my trailer; never had a rack or RTT.

Much of the equation will come down to your torque, HP, and aerodynamics too. I have a stubby front bumper, lift, etc. When I tow, it's a cinderblock pulling a brick.

I got 13-14 mpg on my trip to/from Overland Expo; I was trying hard to maximize mileage.

 

[R_Lefebvre]

I think your big milage impact Bill, is probably because the engine on the Jeep was a little more strained, and the top of the RTT on the trailer is higher than the top on the Jeep.

 

[DrMoab]

I think it depends where you want to go. If you pack up every day, rooftop is really your only option. Offroad trailer is more off road friendly than caravan. An offroad trailer is the best, for me, but it does have consumption impacts.

I'm not so sure about this. I finally got my tent mounted to my trailer and after setting up the tent a couple of times, I think that even if I was packing up every day I would still rather have it on the trailer. It's lower, easier to get the window poles in, easier to move around and tuck in the fabric and much much easier to zip up the cover. On my XJ it was a total PITA to get it zipped up.

 

[OverlandZJ]

I'm not so sure about this. I finally got my tent mounted to my trailer and after setting up the tent a couple of times, I think that even if I was packing up every day I would still rather have it on the trailer. It's lower, easier to get the window poles in, easier to move around and tuck in the fabric and much much easier to zip up the cover. On my XJ it was a total PITA to get it zipped up.

This has been my experience as well. Hanging off the side of my XJ every morning to pack up the RTT got old quick. Carrying a small step ladder made an improvement, but if i'm moving location frequently an RTT on the trailer is so much easier.

 

[STREGA]

I'm not so sure about this. I finally got my tent mounted to my trailer and after setting up the tent a couple of times, I think that even if I was packing up every day I would still rather have it on the trailer. It's lower, easier to get the window poles in, easier to move around and tuck in the fabric and much much easier to zip up the cover. On my XJ it was a total PITA to get it zipped up.

I agree, it is way easier to put away the tent on the trailer than on top of my FJ.

I averaged anywhere from 13.5 to 16 mpg on my trip to the Expo, I was pulling a AT Horizon with a Globetrotter RTT as well as a RTT on top of my FJ also. I'am pretty sure I will pick up a couple of MPG's when I remove the RTT off of the FJ. I usally average about 19.5 to 20 mpg's with no RTT or trailer. I also have a small homebuilt teardrop that weighs about 1000 lbs and average almost 18 mpg pulling it, I don't know yet if the Horizon will get as good of mpg's as the teardrop it is alittle wider, taller and heavier but it's still mostly behind the FJ slipstream so I'am hoping it doesn't have to much impac.

 

[Hilldweller]

I think your big milage impact Bill, is probably because the engine on the Jeep was a little more strained, and the top of the RTT on the trailer is higher than the top on the Jeep.

Yeah; I need a ricer wing on top of the Jeep...

 

[Romer]

I use to have a much heavier Jayco Baja that towing to Moab would give me about 11mpg. Towing the AT Horizoin with the 7" rack for the globetrotter RTT, gave me about 6-7mpg. I made this trip (denver to Moab) twice and put a lower hitch on the front to angle the RTT surface down hoping to have less drag on the second trip, no effect.

It was much easier to pull up hills though, but much more unstable in high side winds which are typical on highway 191 into Moab

 

[Romer]

What I was wondering is if we covered the airgap between the trailer and the top of the trailer, it should cut down the drag.

A simple way is to take a cover like a roof top tent cover that has longer sides that goes from the top of the tent down to the body of the trailer. If you did something like this with a hard V, like a ship hull in the front to deflect air, that should make a big difference. Just looking at pulling a AT Horizon with a RTT gets much worse MPG than a bigger, bulkier and much heavier Jayco Baja

I am just thinking out loud, but it sounds like it should work. First part would be to find a cover that does not let air pass through that's about the right size and see if that makes a difference, then maybe find something to attach to the battery box that is a deflector.

If it works, seems like it should pay for itself pretty quick. And you would think that just eliminating the air gap between the RTT and trailer would make a huge difference