Fuel efficiency

I was curious about fuel consumption when carrying kayaks on the top of a car vs a lower profile trailer. Specifically, we have a 6 cyl toyota 4runner. Not a great MPG vehicle to begin with, but I think about 2 mpg less with our boats up top.

Has anyone done the math? Will a light weight trailer beat out the cartop carrier?

We are considering it for other perks like my wife being able to load our tandem by herself when she wants to take the little one out with her. The MPG alone would not make it worth while, but it is a consideration for which to choose on a longer trip with all three of us.

Thanks for the help.

Generally the smaller the more aero the car the more effect.

I normally carry two 17ft sea kayaks. My Subaru looses up to 4mpg. My diesel powered 3/4 ton truck no discernable difference.

I don’t notice a huge difference with one boat on the roof but there is definitely a noticeable drop with two (I have a 2014 Subaru Crosstrek and average about 28 mpg, almost all of my long drives include a kayak). I’m thinking the trailer might be better than having multiple boats on the roof but might be a wash with just one. They are definitely convenient, as long as you have a place to park them.

With a single boat on top in low cradles, I lose about 2 MPG in my Outlander. A single boat on top in the new-to-me Hullavator, I seem to lose about 3.5 mpg. 2 boats and gear in my kayak trailer and I lose about 4 mpg, and with 4 boats and gear I seem to lose about 5 mpg. These are general estimates based on the trip computer. I consider all well worth the minimal loss.

I carry canoes on a trailer behind a Ford F-350 diesel.
My record mpg is 23.8 mpg.
With a trailer more like 21.5
It can haul more than 2 Subarus.

Thanks to all for the replies. It sounds like others get a similar result with car top carry. The trailer appeals because it seems we tend to over pack, and having a little room back there for the cooler and fishing gear would be nice, but mostly, my wife needs to be able to easily load boats for trips she wants to do on her own. I was hopeful it might actually be slightly better mpg with less wind resistance right behind the car.

Can’t answer you on the results of trailer versus roof rack, but with the 2001 Outback I used to have, I did some checking over time on mileage with stuff on roof or not. I found that the big hit happened when I put the roof rack on (A Yakima non-aero set). Once I put the cross bars on, I found freeway mileage dropped by 3-4 mpg. If I put bikes or kayaks on the rack, I didn’t then notice any significant change in fuel economy.

Seeing similar big hit with putting rack on roof with my current Audi, but haven’t quantified it nor yet figured out if boats on roof lowered fuel economy even more.

Going beyond looking at fuel usage to total costs, a trailer does have added costs. Registration and possibly insurance for trailer, need to have a place to keep it, some launch ramps charge more for trailers than roof carried boats (I can think of one near me where it is free for roof transported, but they charge for trailers), CA State parks charge a trailer as an added vehicle, etc.

Trailers have some advantages. Easier to load and unload and slightly better gas mileage.

However you have to balance that with needing a trailer hookup with electric if you don’t already have one. Finding a parking space. Maintenance, licensing, registration, insurance, and possible property taxes. Higher tolls, storage, etc. In Maryland, DC, and Virginia, almost all car top boats are free to launch, but most counties require a fairly expensive annual permit if you have a trailer.

If you are cursed with a homeowner’s association, many have limits on where you can keep a trailer.

As to mileage, a fellow paddler just kept track and he came back with 5 mpg loss per boat. Both sea kayaks. Compact SUV.

Hauling my kevlar CD Prana on the roof of my Honda Fit has had little, if any, effect on MPG. Get anywhere between 44 and even 52, depending on the wind.

I lose around 2 mpg or a bit less with one canoe on a 4Runner. My '09 Subaru Outback lost more with just a bare rack. You might gain a little fuel economy with a trailer but not much given your 4Runner already doesn’t lose much efficiency and a trailer adds weight and some friction plus at least a little aero drag I’d think.

For best fuel economy lower your rear window and stick them inside.

I see no change in fuel economy with the kayaks on top of our Land Rover Discovery 300 Tdi or when hauling a 6x12 cargo trailer, 30 mpg.

To me, a couple extra mpg when hauling the kayaks is pretty good, I wouldn’t worry about it.

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I find I end up driving a little slower when loaded up with the canoe. I don’t really notice much of a difference but I think that any loss in L/100km is absorbed by the reduction in my speed.

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For straight up fuel efficiency, the toe of rack you’re using might make a difference too. J racks vs saddles, etc. For ease of loading a different rack might be the answer.

There are various racks that have load assistance of different types. Thule Hullivator is a very popular one. I chose the Malone Seawing for myself because of the optional “stinger” load assist accessory, and there are others.

If you want the trailer for extra cargo space, that’s different again, and might be with the other issues people have mentioned just for that convenience.

All are options, it’s just a matter of choosing what’s a priority for you.