Look at the pick ups in the NASCAR series. They all have covered beds and what should be the tail gate up. You can bet that if having it down made them faster they would be down. And I think thay have done enough testing to have a baseline.

 

Are you sure that the pick ups on Nascar Race is identical to the Street pick-ups. A far as the WEIGHT is concern. They made the body to far from the typical pick up body as per weight is concern. In short you cannot just bring your pick up to a race track to race. That means we have all limitation, if yoiu want to drive fast go to a race track not on the freeway. Besides, you can unleashed you maximum horse power if your RPM is above 5000.

 

Ford owners manual recommends bed cover to increase fuel mileage. Ford Engineer told me my 97 had been wind tunneled with tailgate up. I see no difference in fuel mileage on my 05 with gate up or down. I do see about a mpg difference with the cover on. Speed makes the biggest difference in fuel milage on these trucks. Pushes alot of air.

 

Myth busted. Gotta love that show. Proven, by manufacturer as well. Better to have it up. Yah I know just goes against everything you might think it true. Guess it forms a rolling vortex and that helps the airflow off the cab, on the rolling vortex of air in the bed and finally off the rear. Seen it in action, its crazy cool.
Okay I'm done being Mr. Science.

Personally I like my lid and prefer beds be covered. But that just suits my needs and taste. A guy hauling big stuff around all the time might have different needs.

As for the covered beds, I bet you'll find they do it to gain more downforce. The same reason the nascar cars have long trunk lids and big sloaping rear glass.

 

and i want to stab babies!!!!!!!

 

I put my tailgate down soooo I can cruise thru the tollbooths

 

I guess i will have to leave er up

 

Saw a MYTH-BUSTERS about this same issue;and supposedly they got better gas mileage with the tailgate up. They said that when the tailgate is down the air coming down from the cabin has longer to travel as it forces its way down your tailgate creating drag. And when it is up it creates a circular "bubble" in your bed that deflects incoming air away from the vehicle. Oh well, its just a matter of taste, and if it works for anyone. Great

 

ROTFLMAO



Ed

 

Obviously there is a lot of debate on this issue, I can find conflicting reports on the subject all over the internet. The bottom line is some people may get better mileage, some may not. My experience is that in my truck, on the highway, taking the gate off does give me better mileage, between 2-3 mpg increase, maybe not much, but it all adds up. Since I use my truck for business, anything I can do to lower the per mile costs means more money flowing through the business, at the end of the year it can add up.

Now before everyone starts saying how this isn't true, can't be true etc, I'll be more than happy to take anyone who doesn't believe me out for a cruise and you can see for yourself.

Any takers?

 

I'm not even going to bother reading this thread as it defies common sense.
Let's just jump to the big question...

ARE YOU PEOPLE CRAZY?

Here are three reasons why this is a stupid idea.

1) If you drive with the hood up it will ruin your gas mileage, the hood will act as a giant sail.

2) If you drive with the hood up, 'Hello' you can't see where you're going.

3) It's probably illegal and if it is, I hope every ones of you gets a ticket.

 

Ummmm, you're joking right?

If not, you need another cup of that new coffee ya found

 

Tailgate down - air flowing over the cab down into the box creates suction on the back of the cab creating a small amount of drag and right out the back.

Tailgate up - same as tailgate down except the out the back. At that point the air is pushed up and back toward the cab. Enough of this, the air will form a mini-vortex which creates the 'air bubble'. This bubble forces more of the air up over the air bubble and over the tailgate, reducing drag - somewhat as you still have air hitting the tailgate to form the bubble.

The best solution - a tonneau cover.

Some folks have mentioned they get better milage with the tailgate down. If the milage has increased, it is a 99.9% chance that it is because they have 'adjusted' their driving habits to 'prove' their tailgate down theory. If they drove the same way with the tailgate up, they would probably see even a greater improvement.

 

I don't question the physics, but my mileage increases are the result of consistent highway driving over the same route with the cruise on, same gas and over a variety of weather conditons.

When it comes to aerodynamics, as a former pilot that still belongs to the EAA, I can say without doubt that very small changes in designs can result in rather significant changes in performance. My father and I built a BD4, apparently we didn't get the vertical stabilizer aligned because it had a pull to the left that took almost 75% of the trim to correct at times. We finally corrected it with a piece of aluminum about 4" long and 2" wide, bent to offset the pull.

I have a flareside, I would think the aerodynamics of my truck are significantly different than a standard bed for instance. How high off the ground or the angle the truck sits at, objects in the box etc, all could affect aerodynamics significantly beyond the configurations that were used in testing for this purpose.

I've seen tests that indicated the ideal setup is a tonneau that only covers the 2/3 of the bed from the tailgate. Who knows.

Anecdotal evidence often conflicts with science and it can't always be explained away as a "placebo" effect when the evidence shows the affect is real.

I will say this, even with the tailgate down, if I'm not on the interstate where I can maintain a constant speed, then the increase isn't so great.

 

What does an across the bed tool box do?

What about the tool boxes that run legth wise and sit on the rail?

Now if only my bed was ever empty and I also happenbed to feel like tearing up my truck, then I might test the tailgate down theory.