Just saw on Mythbusters that you get slightly better mileage with the tailgate up due to some vortex being formed behind the cab with the tailgate up. This may have been mentioned some time back but don't recall, maybe due to the rum.

 

Maybe stop by the 73-79 forum

Our tailgate thread is going strong

 

The Mythbusters test method was a royal POS but then they frequently are. They need some better tech experts on that show...

 

sounds interesting though

 

aaahhhh tourque1st I have to disagree with you!!! I think there awesome, you couldn't replace adam and jamie. Now granted they were special effects people before scientists... or something like that. However they bring to the show a unique brand of testing that is characteristic of that show. Test the hypothesis with whatever means we have available, in the most scientific manner possible. I think they whole heartidly accomplish that. What better way to test than to drive two similar trucks for a distance, one with the tail gate up and one down? Now granted, you put my dad in one truck, and me in another and you'll probably get two totaly different mpgs, we have different driving styles(surprisingly I get higher mpg). That is there main flaw with that perticular experiment.

All in all, I think there alot of fun, no it's not always the most "scientific" but the way they do it still gets pretty good results and is alot more fun!

Anyway, I guess the point is.... keep it up!

-myers

 

I like them too.
BUT, I think it would have been much better to do the same test back home with the tailgates reversed.

Thats my narrow minded opinion and Im sticking to it.........

 

I'm thinking you could save more gas by losing weight:

Heavier drivers seen using more gasoline

1 billion gallons a year more because we are fat.

-Jim

 

That's funny. I always thought fat drivers produce more gas!

Seriously though, I find this interesting, that overweight drivers can reduce fuel economy. I'll bet the amount could easily be offset if everyone kept track of their tire pressure though.

I saw the "myths revisited" show last night. They re-tested the tailgate up or down thing again. This time they did a quick test, measuring the fuel consumption at a specific speed. They also threw in a few more tests. One was the goofy net thing in place of the tailgate, and the other was no tailgate at all. Turns out that the net gave the best mileage! I wont run one though, since they look just too ugly for my taste.

 

yeah,last night they re-did the test with a dakota.yuk.did anyone see the one when they tested the air conditioning vs windows down?the one with the ac on ran out of gas way before the other one.

 

Imagine if everyone kept their tire pressures correct AND lost 10 pounds. Next headline on CNN: "Fat Chicks Support Terrorism".

It would have been interesting to through in a tonneau cover in that test as well.

-Jim

 

Actually, they did. It replicated the results of the tailgate up. No gain.

 

Common sense tells me that no tailgate should give the best mpg. (least amount of air resistance and least amount of weight) But in any case, other factors such as temperature, humidity, wind, road surface, day/night, etc., may have more effect on mpg than the position of the tailgate, so to get a statistically valid result, they would need to account for all these, plus drive quite a few miles. I'm not sure how many miles they drove, but I'm pretty sure that they didn't compensate for at least some of the above factors I have listed.

However, there is one way to get valid data (even if not mpg) without all these. Put the car into a wind tunnel, and test its ait resistance with different tailgate configurations, and the one with the least resistance and possibly with the least weight should get the best mpg. For this test the engine doesn't even need to be turned on, so that removes many unknowns, and since all these tests can be done in a matter of few minutes/test, there is no need to worry about differences in temperature and humidity either.

 

Wind tunnel testing has been done. With the gate up a votex is created in the bed forcing the airflow that comes over the cab to stay above the bed and then drop after the tailgate in a similair manor to what you would expect with a topper. With the gate down the votex area is reduced enough that the air drops down roughly behind the axle and increases down force thereby increasing drag.

 

FWIW -

Supposedly, the tailgate is a structural member on newer pickups; driving for long periods with the tailgate down/off can cause the rear fenders to flex and eventually cause metal fatigue. True.........who knows?

Steve

 

I believe that about the metal fatigue. We have seen some covers that didn't fit as well because the measurements were slightly different from what someone would normally see on their truck bed. Also, there have been other tests done about the tailgate in the "up" position being better for fuel consumption. So I believe that about the Mythbuster's experiment. However, all the tests I've seen in regards to tonneau covers saving gas it has shown that it does help. The only case I saw where it didn't help was on a Ford Ranger with a hard cover on it. But, all the soft covers showed improvement.