Roof top tent mounting heights vs MPG

Once I saw your truck. Instantly I thought of this.

 

Mine also came with free satellite 5G

 

I have mine mounted at the exact same height and saw about a 1mpg drop from 21-20 on the highway and it's probably more related to the additional 250lbs between rack and tent added to the back.

Bugs on the tent are a good indicator of airflow. If your front end and windsheld are splattered and your tent clean (mine normally is) then the air off the windshield is going over the tent and the additional drag is minimal.

 

I would be careful with how low you mount your tent. If mounted below the roof line, the roof can cause interference with the tent poles that are used on the tent windows. The top of my Cascadia tent sits flush with my prinsu rack and I can't use the tent poles on the fronts since they interfere with the roof. I'm forced to tie the window shades to the prinsu rack; not a big deal, but for a several thousand dollars I wish I had considered this before.

 

I used to have the full height KB Voodoo rack with a Tepui and my friend had the same truck and tent with the KB Voodoo low mount. There was only about 1 mpg difference between the two on a trip we took with him following me. The mpg took a pretty good hit at interstate speeds compared to normal.

 

I already can't use the poles on the side opening toward the cab, so it wouldn't change anything there.

 

That's interesting and very helpful. I don't know if the hit I'm having now will really be any different if I get a lower rack. I'm sure some of the drop is due to the extra 250 pounds in the bed, which isn't going to change with a lower rack.

 

I live in Vegas, I haven't seen any bugs on my windshield or tent since I put it on a couple weeks ago, but that's a good point to watch out for, I'll check it next time I drive somewhere with bugs.

 

Just a quick update; while I am deciding what I want to do with the rack height, I played around with the placement of the tent. I found that having it further toward the tailgate increased wind noise and hurt the mileage even more. I ended up scooting it up as close to the cab as I could while still reaching my arm in to unzip and found that I gained back a respectable chunk of my mpg. When I first placed the RTT I lost about 3-4 depending on speed, but with it all the way up I'm closer to 1-2. That's about what I have heard from others and a small enough drop that I'll probably just lower the rack the 2 inches and call it a day.

Just in case anyone else is having the same issue, moving the tent all the way forward made an immediate difference in noise and mpg for me.

 

I wonder if one of them fancy roof racks with the wind deflector would help at all.

 

Mine is mounted low - sits about 3 inches above the sides of the bed and I have it pushed up close to the cab. Barely any hit to mpg like this but its a pain to get the cover on and off being that close to the cab and I can't use the poles on that side for the window.

 

I doubt it. I have a Prinsu with deflector and without the RTT (just the rack) I saw a drop of 2 mpgs. The tent was good for another 2-3 mpg loss on top. I may try pushing it toward the cab as suggested, but I'd prefer not to lose the functionality of the front tent window.

 

One time when driving to Moab I noticed another RTT on top of a vehicle going down the highway. Holy frijoles was that cover bulging up large and causing a massive amount of drag! It was pulling up where the ladder is and made a scoop pretty much. So ever since then I use kayak straps to help secure the cover and prevent it from bulging up like that. I also got in a habit of just leaving as much as I can up in the RTT so that the cover fits without slack. Give that a go before changing a bunch of stuff up. BTW I have the KBVooDoo mid rack as well just without the bed cover adapters so I sit just a little lower then you

 

I have the same set up as you. I have the KBVoodoo backflip tonneau brackets which give it 2 inches added height on top of the 10" rack that I have. Surprisingly, my MPG has actually gotten better. I went from about 15-17 mpg without the rack and RTT but when I added it all, first trip I took had me around 18-20 MPG going around 75 mph on average through the windiest parts of Palm Springs and near the Salton Sea.

Everything stays on my truck for the most part but will eventually build storage for the RTT in my garage in the near future.

 

Streamlining helps. Im regeared and full armor. I get ~230 miles to a tank. But i also didnt get a truck to get good gas mileage..

 

I don't know how you all get such bad mileage, except for those with big wheels and tires and major mods. I have tracked my mileage by hand in a log book since I got the truck 4 years ago, and I typically average 17-20 mpg even with the rack and tent, and usually 18-19 with everyday driving. I never saw a drop off once I added the tent 2 1/2 years ago, nor with the wooden platform and trays and all the camping equipment added. I don't pay attention to the MPG on the dash as I keep track of mileage and gallons per fill up and just do the math. The only time it really changes is with lots of travel in 4wd, lots of mtn driving, or pulling the trailer, and even then it doesn't get bad compared to what I have read from many of you. Maybe I just drive like a lil ol' man now.

Edit: I also have a Pelfreybilt steel front bumper, and RCI steel skid plate, so there is even more added weight. Last tank fill up was 329 miles, and the dash said I had 17 miles left. I do use 89 octane, and never top off the tank once it auto stops.

 

2017 Tacoma, before the tent I was averaging 15 around town now I’m averaging 17mpg in town Somehow gained mpg. If you believe the gauge.

 

If it makes anyone feel better I averaged 10-12 on my trip from salt lake to central california I did run into some heavy winds and had a full bed along with cbi bumper and front skid

 

Ive had my tent on my truck about a year and my MPGs suffered horribly. The MsPG didn't bother me though...being blown around like a sail and struggling to go up hills did. I drove home from work today which was super windy and that was it for me..so I tore it off. I built my rack and plan on building another that sits lower.

 

lol statements like this are so annoying. Speaking for myself and at least a few others on this board...my tent is somewhere in the range of 170-200lbs, the truck is too high to fit in the garage, and the garage door construction is not conducive to any sort of jerry rigged device to get the tent off. I live alone, or with a 5'1" girlfriend, and all my friends are 30 mins apart.

Am i planning to never remove the tent? No. Are my options to remove the tent severely limited by a multitude of factors? yes. Not all of us leave our tents on our truck just to seem cool to everyone else.

To OP...a 4-8MPG hit seems pretty excessive, mine is mounted on a 12" rise bed rack, so it sits just about where yours does. My MPG is down to about 14.5 from 18-19 when i got the truck, but that's also with addition of nearly full armor, lift, bigger tires, etc.

I would try doing real MPG calculations for a few tanks each with both the tent on and off and see if it's really just due to the tent, and not due to other factors like weather, differences in driving, etc. For what it's worth, the weight/height of my RTT don't affect my MPG more than a half gallon or so, with all the other ish i have on there.


Here's me, parked in my work parking lot, flexing on everyone who drives by

yup...i can't fully open up the front window of mine either...just one side. At some point I will probably rotate the mounting rails of mine so I can open it off the back...maybe.