Value of a Tonneau Cover

[Andy Williams]

Just bought a new ST that does not have a cover on the back. Logic tells me that a cover will help gas mileage, but I got some story from one dealer that the ST was designed so that a cover was not necessary and didn't help MPG. Can anyone give me the straight dope on this?



Thanks

 

[Larry Phillips]

Doesn't help. Bed's so short the air flows over it anyway. Actually, I think they proved that a lid doesn't help MPG on a normal truck either on Mythbusters. I've got a Snuglid, and I haven't seen any differance between now and before I installed it.

 

[Kevin Palmer]

Larry is correct. You can also check out the MPG link to see what others have gotten. It will give the details as to the equipment on the Trac so you can compare apples to apples,,,,

 

[Kevin Palmer]

Here is the link

 

[Dale Carlson]

This question comes up every so often. A scientific test by the University of Michigan (link below) shows a 22% decrease in drag for a full-size truck with a bed cover - I'm not sure how that translates for short-bed trucks, though, or how it would relate to gas mileage.



And Coastiejoe, there are configurations in the MPG reports (that don't include the "performance" mods) that will show an increase in gas mileage when the only difference is having a tonneau cover. Usually not much, but it's there.



Anyway, afwill, there's lot's better reasons to get a tonneau cover of some type than just a (questionable) gas mileage increase.

 

[FlipTrac_511]

I didn't see an improvement in mpg. I don't know how my A.R.E. LSII tonneau affects the Trac aerodynamically, but physically this lid adds some weight to the already heavy Trac. Perhaps the aerodynamic advantage the lid provides is negated by the lids' own weight. I'm glad I have it though, as I frequently stow bulk items back there that I don't want exposed for all to see (and steal).

 

[ben beethe]

afwill,

thanks for asking this question. I was too wondering the answer to this.

 

[shawn stonbraker 2]

I got a soft tonneau cover and no difference in mileage. It just helps keep the luggage from getting wet on trips.

 

[Richard L]

I have had a hard tonneau cover on both of my Sport Tracs and I seen no difference in MPG with the tonneau cover on or off.



There could be a slight difference but it's to insignificant to notice since traffic, weather and other conditions would account for even larger variations.



...Rich

 

[Kerry Matthews]

No mpg value, but for versatility, it can't be beat! That folding tonneau is like the greatest thing since sliced bread! THAT alone is the biggest reason I don't want to buy an F-150 when the Trac wears out. Too bad Ford doesn't make one for them...

 

[Mark Stuvetraa]

Larry Phillips/NX-01 is correct...



The Mythbusters actually tested whether or not having the tailgate down on a truck produced better gas mileage then keeping it up...



They started testing by having two F-150's (exactly the same options, etc) both filled with the same amount of gas, and drove them until the gas had run out. The truck with the tailgate up went 30 miles farther than the truck that had the tailgate down...



The next test was to see how this was possible. They built a tank with water circulating around it, and then put particles into the water. There was a scaled version of a F-150 sitting in the flow, and you could see the particles flowing over it (simulating a wind tunnel, but with water)...



They first put the tailgate up, and then down...



With the tailgate up, an initial vortex forms, and remains in the bed of the truck. This vortex causes all the subsequent wind to clear the tailgate...



With the tailgate down, the particles would go over the cab, and hit toward the middle of the bed (no vortex) This causes drag, and thus the potential for less gas mileage...



It was pretty interesting because I always thought having the tailgate down reduced the drag due to the wind hitting the tailgate, and the result would be better gas mileage...



The same principle can be applied to the Tonneau Covers as well. Without the vortex, the wind will hit the middle of the Tonneau Cover causing the drag on the back (maybe a spoiler would help here???)...



Mythbusters Rule (awesome show)!!!

 

[Andy Williams]

Great commentary guys. I'm going to like visiting this site for information almost as much as driving my ST.

 

[Dale Carlson]

Krash, you ever look at the Advance covers for the full-sze trucks? I think they even do three-and four -panel covers.