Wind Deflector

[Dave Storey]

Hi just want some input on the wind deflector pictured here , I have one similar .
I own a 1998 Buick Park Avenue and toll a Trillium 4500 behind her . Just wonder if I would save gas with this wind deflector installed on the rear part of the roof ? Will be travelling the 401 eventually

[Darwin Maring]

I wouldn't want to mess up the paint on my car just to get an extra mile per gallon.

[Byron Kinnaman]

Originally Posted by Darwin Maring

I wouldn't want to mess up the paint on my car just to get an extra mile per gallon.

I agree.
According to discussion on RV.net there's no appreciable benefit. They're talking about pulling much bigger trailers that less aerodynamic. Save you time, money, and vehicle paint.

[BCDave]

I had one of those a LONG time ago - can't even remember what I was hauling - or what car (or truck) I had used it on. It may have been on the roof of a pickup that had a big cargo-box mounted on it. Anyway - I never noticed ANY difference between having on and taking it off whatever the heck it was that I had it on. I know this because I DO remember that it was "the world's easiest decision" to take it off and sell it!

(And which rain gutters were you planning on attaching it to? Your Buick doesn't seem to have any!)

[Dave Storey]

Thanks for the input .

I will probably sell it at my next yard sale or I might try it to see if it does make a difference ,the buick has a mpg average indicator in the car . I did have it attached to the roof and it hooks up pretty good .

Maybe I will make one of these for the front of the trillium ,just kidding

[Andrew Gibbens]

Volkswagen tested roof spoilers in its wind tunnel back in the 1980s when they first became popular and found a significant effect.



The top case has a Cd (drag coefficient) of 0.53 and in the second case with the roof spoiler, that drops to 0.45 - a 15% reduction. In round terms you would expect a 15% drag reduction to give a 15% improvement in fuel economy.

If I had to choose the accuracy between an internet discussion and an automobile manufacturer's published wind tunnel data, hmmm, let me see..... I'll pick the wind tunnel.

The third case shown was what has become the standard design of European trailers with a sloping front. This has exactly the same drag as the square-fronted trailer, but does not get a light tongue weight at speed - both the other two cases suffer from that.

(PS first posted 2006, I see)

[Tim Wood]

Dave, What did you make the wind deflector out of ?

[Kenny Strong]

my sister and I have 13' trailers towed by 4runners; we went for 2 months towing. they had a deflector like yours. every time we stopped for gas they paid aprox $10.00 more. they took it off after 3 fill ups and every fill up from then on was about the same.

[Byron Kinnaman]

Originally Posted by Andrew Gibbens

Volkswagen tested roof spoilers in its wind tunnel back in the 1980s when they first became popular and found a significant effect.



The top case has a Cd (drag coefficient) of 0.53 and in the second case with the roof spoiler, that drops to 0.45 - a 15% reduction. In round terms you would expect a 15% drag reduction to give a 15% improvement in fuel economy.

If I had to choose the accuracy between an internet discussion and an automobile manufacturer's published wind tunnel data, hmmm, let me see..... I'll pick the wind tunnel.

The third case shown was what has become the standard design of European trailers with a sloping front. This has exactly the same drag as the square-fronted trailer, but does not get a light tongue weight at speed - both the other two cases suffer from that.

(PS first posted 2006, I see)

Most of us don't tow with a hatch back. It usually a truck, or an SUV. So much of this depends on the tow vehicle and trailer combination. From what I've read deflectors until you get to really big trailers and 5th wheels do nothing. Boler, Scamp, Casita are rounded enough to greatly reduce drag.

I don't believe I could gain back the 1 to 1.5mpg penalty I have when towing.

[Darwin Maring]

We don't tow in a wind tunnel so have no need for a wind deflector.

[BCDave]

Originally Posted by Tim Wood

Dave, What did you make the wind deflector out of ?

Mine was purchased (somewhere) - likely at Canadian Tire, so it was essentially identical to the one in the picture - aluminum some sort of plastic, rubber suction cups and straps with hooks that attached to the rain gutters at roof edge

[Darwin Maring]

My wife wants me to Google to see if someone has designed a Wind Deflector that will attach to my blue jeans rear belt loops.

[Dave Storey]

As long as you don't light a match ,it may cause a fire and then smoke signals at the same time .

[Darwin Maring]

And Dave, That would be really bad in a wind tunnel as it would look like a blow torch.

[Andrew GPSMapNut]

Dave, if you are thinking about selling it, I may be interested in buying it. I'm in Mississauga. Maybe I could adapt it to my Rainier SUV. On a SUV, the deflector could be much closer to the trailer than on a roof of a sedan and I'm convinced that it would save more gas. Right now, when towing, I'm burning 50% more and I know that it's not the weight but, wind resistance. When I towed a heavier but low (pop-up) trailer, it hardly affected my mileage.