This post is about my homebuilt air ramp or deflector and the fuel savings from it.We are running a 2010 Chevy with 6.0 gasoline, 180k miles. Cargo trailer that I added a 9,000btu mini split, condenser mounted on front. Live in Indiana. Few years ago, step 1 was I built a "luggage rack" on the van, based on a commercial ladder rack that clips onto the gutter rail, but lowest possible to roof without paint damage.Van not pulling a trailer gets about 13.5-14 MPG whether loaded or empty. All values as reported by Chevy dashboard, and backed up by occasional hand math from gas reciepts. Our first trip with van and cargo camper got us 6-7 MPG. About 70-75 MHPFew years ago, we drove/towed to Yellowstone NP and Arches NP, with an 8' long air ramp made from OSB plywood and open sides. This got us about 7-8MPG and a few odd looks and questions.This year I built an 8' long, 18" high to match the trailer, and enclosed sides air ramp, open at the back. We drove to San Deigo CA using the Flagstaff/ Yuma route. Going west empty, the best we got was 11.3 (dashboard). About 70-75 MPH. Going east, we were loaded with a family moving to Sommerset KY. From the picture, you might guess we were loaded heavy. For the eastbound trip, 65 MPH, we got 10.5 MPG.The air ramp comes off with 6 bolts, and is stored in my barn.My hope is that this info helps someone else. My numbers are not scientificly accurate.

You will even get better economy and handling, if you would get your setup level, You need an equalizing hitch in the worst way.

If you google this subject you will find lots of equally unscientific studies. The mpg improvements with an air deflector are likely to be very small and only present at high speed driving. The extra weight is likely to yield negative results at lower speeds.Anyone interested can google testing by the YouTuber, Marion Blair. He found no benefit to offset the cost of installing a deflector. His studies seem to be a bit more scientific than most.

Most long haul trucks have skirts now, and I always wonder if those little air deflectors work on RVs like the website says they do. Regardless, ~$1200 gas savings each way is worth a couple hours of labor, hundred bucks of wood and some!.looks. Thanks for sharing

Problem is the testing isn't consistent. Individual trips can have different MPG. Particularly the switch from 70-75mph to 65mph could easily be the biggest impact on MPG and could explain all the increase.Loading can also impact MPG if going thru mountains. I track fuel use and for the same rig loaded the same way, I've seen it vary from 7 to 16 MPG.

Eleven years ago I had a 22' 5,600# TT that I pulled with my F-150 SCAB with the 5.4LV-8.I found a wind deflector from a firm out of Canada and for less than $300 I took a shot.It was easy enough to install and or remove when not towing and I used it for 3+years with very good results. I don't remember what gas costs back then but it consistently got me an additional 1.5 mpg and paid for itself in 6 months. I based the fuel savings on repeated trips to locations I had visited before, my Scan Gauge and at the pump computations as well.Without the deflector the front of my trailer was a always covered in bugs but when towing with it the front o fthe trailer was always clear and clean as the air flow was clearly being deflected up and over the front of the trailer.A mother factor that contributed to its efficiency was having it mounted so far back, at the rear of the shell. I doubt it would work as well if i thad been mounted on the cab of truck with no shell.Lots of skeptic's out there but I know it worked for me.:C

Air Deflector Van + Cargo Trailer Fuel Improvement

eHoefler
Explorer II
Jul 16, 2023
You will even get better economy and handling, if you would get your setup level, You need an equalizing hitch in the worst way.
JimK-NY
Explorer II
Jul 16, 2023
If you google this subject you will find lots of equally unscientific studies. The mpg improvements with an air deflector are likely to be very small and only present at high speed driving. The extra weight is likely to yield negative results at lower speeds.

Anyone interested can google testing by the YouTuber, Marion Blair. He found no benefit to offset the cost of installing a deflector. His studies seem to be a bit more scientific than most.
PartyOf_Five
Explorer
Jul 16, 2023
Most long haul trucks have skirts now, and I always wonder if those little air deflectors work on RVs like the website says they do.

Regardless, ~$1200 gas savings each way is worth a couple hours of labor, hundred bucks of wood and some!.looks. Thanks for sharing
valhalla360
Navigator
Jul 16, 2023
Problem is the testing isn't consistent.

Individual trips can have different MPG. Particularly the switch from 70-75mph to 65mph could easily be the biggest impact on MPG and could explain all the increase.

Loading can also impact MPG if going thru mountains.

I track fuel use and for the same rig loaded the same way, I've seen it vary from 7 to 16 MPG.
Desert_Captain
Explorer III
Jul 16, 2023
Eleven years ago I had a 22' 5,600# TT that I pulled with my F-150 SCAB with the 5.4LV-8.
I found a wind deflector from a firm out of Canada and for less than $300 I took a shot.

It was easy enough to install and or remove when not towing and I used it for 3+years with very good results. I don't remember what gas costs back then but it consistently got me an additional 1.5 mpg and paid for itself in 6 months. I based the fuel savings on repeated trips to locations I had visited before, my Scan Gauge and at the pump computations as well.

Without the deflector the front of my trailer was a always covered in bugs but when towing with it the front o fthe trailer was always clear and clean as the air flow was clearly being deflected up and over the front of the trailer.

A mother factor that contributed to its efficiency was having it mounted so far back, at the rear of the shell. I doubt it would work as well if i thad been mounted on the cab of truck with no shell.

Lots of skeptic's out there but I know it worked for me.

:C
bucky
Explorer II
Jul 16, 2023
A lower to the ground front deflector on the tow vehicle will do the most good.
Newer Rams have the front deflector set up to lower 3 inches at speed.
TFL has tested trucks with a tonneau and without for good provable improvements.
I can see where the deflector that far back should do some good but hard to measure/prove. Side winds can play havoc with MPGs.
On our previous dually/fiver Cummins running at 65 rather than 70 we picked up 9/10s of a gallon.
I haven't played with the new van/TT for mpg as we have only done 150 mile or so trips so far.
valhalla360
Navigator
Jul 16, 2023
Desert Captain wrote:

Another factor that contributed to its efficiency was having it mounted so far back, at the rear of the shell. I doubt it would work as well if i thad been mounted on the cab of truck with no shell.

This is why semis use them effectively on pretty much all standard trucks. The trailer and hitch are largely standardized, so the deflectors can be tailored to match very closely to the front profile of the trailer with a very small gap.

It also helps when semis drive 50-100k miles per year, so small improvements to MPG quickly add up to a lot of $$$$.

For RVs, the truck profiles, trailers and hitch setups are all over the place and too few miles to get a really good idea of the impact, so while great in theory, very hit and miss in practice.

I've often thought that a heavy canvas that extends from the back of the truck cab (you could use the stake holes in the pickup bed) to the top leading edge of the trailer (sturdy attachment points would be needed) should be quite effective. The trick is developing a system that deploys quickly and easily and can accomodate turns.

But reality is most RVs only travel 2-3k miles per year so for most even if it does make an improvement, it's still not cost effective.

For the OP building his own, the cost should be pretty low and there might be an improvement but the data provided isn't clear.
Fisherman
Explorer
Jul 16, 2023
#1 issue is speed, bet if you drop to 65 max you'll notice the fuel gauge doesn't drop like a rock.
dodge_guy
Explorer II
Jul 17, 2023
When I had my TT I found an old fiberglass wind deflector on Craigslist. Modified it to bolt into the roof rails of my Excursion. I gained .5mpg with it. Now that may not seem like a lot until you are on several 3-4K mile trips, then the savings adds up. I only paid $75 for it. Another benefit was that it kept the bug splatter off the front of the trailer!
Boomerweps
Explorer
Jul 19, 2023
I experimented my two camping trips trying to keep my speed down to 65mph on the interstates for mileage. I did not keep as accurate a log as possible & just went off the truck computed MPG. I used the cruise control set at 65 as much as possible on the first trip, 500 miles total. Second trip, about 250 miles, I just kept up with traffic about 70mph, sometimes hitting 75mph.
The truck calculations said I got better mpg in normal transmission mode over tow/haul mode when towing. On my first, slower trip, I locked out all overdrives (8,9,10), using tow/haul every time I thought of it (reverts to normal on startup). On the second, I mostly just kept 9 & 10 locked out. That one level of overdrive, in flatter road sections, seemed to make the difference, even though at higher speeds. I intentionally left normal mode on after initially forgetting to select tow/haul.

Yes, wind is a variable factor in mpg. BUT it is out of your control, last I knew ;)