Cargo box on trailer hitch vs roof

[atitus]

I'm trying to decide what type of cargo box to get. Going to have some long family trips coming up and will need the space. Roof racks are expensive plus I am worried about mpg. Anyone have a trailer hitch mounted cargo box and how have you liked it? How bad does it affect mpg? Thanks!

 

[Bopper]

On previous vehicles I have used a hitch platform, with a packed giant cooler and 4-5 folding chairs strapped to the top of that. The cooler serves a multi purpose, because you will ussually need a cooler when you get there. I plan on using the CX5 the same way. I am going to install the Curt class II wih a 1.25-2" extention, because the platform is a 2". The extension will also allow the hatch to swing open while the platform is loaded. The fact that the back window doesn't open makes it difficult to preload the platform, it doesn't open does it?
Never use bungees, use ratcheting straps.

 

[SmurfaceWarfare]

I would imagine having a hitch storage system would block the rear camera. As well as you need the extension to open the hatch, and it would make getting things out of the back very hard having to bend over it. I would personally go for on the top. It is out of the way, won't have to move around anything to get into the back of the vehicle. Plus you can get other additions to the roof rack for future use, bike racks, kayaks, anything you want. Up front cost is more, but you can do more with the rook rack systems making them cheaper in the long run.

If you factor in the cost of the hitch they are equally expensive to get started.

 

[SmurfaceWarfare]

I just thought of another point. If you get the hitch mount you can move it from vehicle to vehicle. With roof racks they are vehicle specific most of the time. So you can't move it to another car, and when you sell the car you will have to buy another one. That has made me re think the hitch mount.

 

[Bopper]

This is the fourth car that will be using the same hitch platform. Using the adapter/extension allows room to stand between the car and platform. I have a THULE cargo basket that I have used on my Expedition In the past. I like the baskets because you are not confined by the shape of the carrier. With the expedition I had to carry a step ladder to reach the top.

 

[JTNY]

I wanted to do the same setup with the Curth Hitch. But does the Curt Class II have a 2" hitch opening? or is it 1.25"?

 

[atitus]

Thanks everyone, this has been some really great feedback. Its good to hear that some of you have used these hitches before. For those of you who have been using them, how much of an effect does it have on fuel efficiency? Noise?

 

[NinjaNoises]

But roof mounted boxes look so much cooler

 

[Bopper]

The curt I/II is 1.25", the III is 2". There are other brands out there also. Most hitch accessories will bounce and rattle around when they are unloaded, once loaded they quiet down and are usually silent until you jump some railroad tracks. Effect on mpg will be small and mostly from weight as opposed to drag, you'll get the effects of both loaded up top. The camera will be blocked, so you will need to exercise the short term memory, and the neck, when in reverse.
A concern that i did always have, was the fact that the rear license was not visible from behind because of all my stuff blocking it. Many police have passed me by without a concern, maybe it would have been different if I were passing them.

 

[CCR76]

Rooftop rack with Yakima Skybox 12 costs me about 3 mpg on the highway compared to bare roof. I use Yakima towers on fixed mounting points, and needed to build a simple frame of pipes to add a third crossbar so the box can be mounted far enough forward to clear the hatch. It took awhile to figure out but now that it's set up it is easy to put on and take off and works well. I debate pulling a small cargo trailer instead; expect less of a mileage hit but it's one more big thing to store and two more bearings and tires to potentially fail at an inopportune time.

We go on a summer trip every year in my Jeep Wrangler fully loaded and pulling an 18' lightweight guideboat on an aluminum trailer and get better gas mileage than unloaded without the trailer. I am convinced the trailer in that case has some kind of helpful aerodynamic effect, although I don't know it would work the same way with the CX-5.

 

[jcarroll07]

We go on a summer trip every year in my Jeep Wrangler fully loaded and pulling an 18' lightweight guideboat on an aluminum trailer and get better gas mileage than unloaded without the trailer. I am convinced the trailer in that case has some kind of helpful aerodynamic effect, although I don't know it would work the same way with the CX-5.

Probably because Wranglers have the aerodynamics of a brick to start out with.

It sounds to me like the hitch mounted cargo box would be the best bet for a CX-5, provided it's positioned such that you can open the rear hatch unimpeded.... though you have to bear in mind that the stated weight limit of the tongue is only 200lbs, so it would serve best for items with more bulk than heft.

 

[BacklashZ06]

This is the fourth car that will be using the same hitch platform. Using the adapter/extension allows room to stand between the car and platform. I have a THULE cargo basket that I have used on my Expedition In the past. I like the baskets because you are not confined by the shape of the carrier. With the expedition I had to carry a step ladder to reach the top.

I use a THULE enclosed cargo carrier on the hitch, no cost to MPG and it easy to move between cars if I wish. The THUE system is such that it will not effect the opening of the back hatch and it comes with an adaptor to use with a 2 inch hitch, so it works with both a 1.5 and 2 inch receiver.. It has lights built in and the ability to relocate the back license plate for longer trips.

 

[crashtx1]

Cargo Box hurt mileage

I use a THULE enclosed cargo carrier on the hitch, no cost to MPG and it easy to move between cars if I wish. The THUE system is such that it will not effect the opening of the back hatch and it comes with an adaptor to use with a 2 inch hitch, so it works with both a 1.5 and 2 inch receiver.. It has lights built in and the ability to relocate the back license plate for longer trips.

We decided to add the rack and rails(yes, expensive) to carry our Yakima SpaceCadet. While not as sleek as ski carriers, the SpaceCadet is very aerodynamic, and we have used it on mini-vans in the past with very little MPG hit. We just made our first trip with the topper on and gas mileage suffered greatly. We get 28 mpg in city/highway, but on this trip we averaged 22.5. We were driving from Richardson, TX to Corpus Christi, and some of the drive was very windy, but the worst MPG was actually on the less windy parts of the drive. Very unhappy since we spent $500 on the rack/rails, and now I'm not sure I'd ever want to use them again.

 

[MikeM.]

We decided to add the rack and rails(yes, expensive) to carry our Yakima SpaceCadet. While not as sleek as ski carriers, the SpaceCadet is very aerodynamic, and we have used it on mini-vans in the past with very little MPG hit. We just made our first trip with the topper on and gas mileage suffered greatly. We get 28 mpg in city/highway, but on this trip we averaged 22.5. We were driving from Richardson, TX to Corpus Christi, and some of the drive was very windy, but the worst MPG was actually on the less windy parts of the drive. Very unhappy since we spent $500 on the rack/rails, and now I'm not sure I'd ever want to use them again.

Obviously, roof rails, rack and rooftop cargo box are going to add considerable drag at freeway speeds. I would only use a rooftop solution as a last resort on a long trip. But some installs are considerably worse than others.

More important than how "sleek" the cargo box looks, is it's mounting position in relation to the vehicle. The behavior of air flow and the resulting drag is often very sensitive to slight differences in mounting position. Although it's often counter-intuitive and difficult for most people to predict whether a change in shape/position will increase or decrease drag, as a general rule the box should be mounted as low to the roof as possible and centered on the body. Yes, this makes it more difficult to access so it may not be practical, I'm just saying it helps reduce drag (especially keeping it close to the roof). Sometimes tilting one end slightly higher or lower (just a 1/4" or so) can make a big difference (although this is hard to determine without specialized testing).

Drag accounts for over 80% of the energy consumed at 70 mph and a top box just makes it worse.

 

[bta]

We decided to add the rack and rails(yes, expensive) to carry our Yakima SpaceCadet. While not as sleek as ski carriers, the SpaceCadet is very aerodynamic, and we have used it on mini-vans in the past with very little MPG hit. We just made our first trip with the topper on and gas mileage suffered greatly. We get 28 mpg in city/highway, but on this trip we averaged 22.5. We were driving from Richardson, TX to Corpus Christi, and some of the drive was very windy, but the worst MPG was actually on the less windy parts of the drive. Very unhappy since we spent $500 on the rack/rails, and now I'm not sure I'd ever want to use them again.

Is 5.5 mpg difference really a big deal for the occasional use of a roof top carrier? On a 425 mi trip, isn't that only 5 gallons more or maybe $18 bucks? Seems like a small price to pay for the flexible increase in storage space. Doesn't seem like a reason to no longer want to use a $500 rack/rail system. Maybe I'm confused because I only use my roof top carrier twice a year.