Tailgate open = Better Gas Mileage?

Put truck in wind tunnel with tail gate up. Put truck in wind tunnel with tail gate down. Put truck in wind tunnel with tail gate removed. Compare the 3 coefficients. technically the only way to do this. To many other variables.

 

My wind tunnel is in the shop this week - getting a new fan belt.

 

I think that it could be different on certain trucks but it is never going to make that big of a difference so don't sweat it and leave your gate up.

 

Best to leave it up anyways. Those steel cables supporting your tailgate when its down are not shock absorbers. While I don't think it will hurt the tailgate itself, the cables take a beating. But when those cables break and your tailgate begins bouncing off of your bumper...

 

Plus, if you drive around with the tailgate down with nothing in the bed, you just look stupid.

 

Also known as an eddy in river terms, or a set of vortices to an aerodynamicist.

Here is what you are looking at with that leaf:

 

Hey, let''s ALL do it > maybe it will start the next illogical trend.
Then.... we'll all stop.

 

Correct, pay the man

 

http://www.youtube.com/watch?v=r3aqHbD-O9E

 

Absolutely true. Well said.

http://monarchrifle.com/dougs_tacoma.html

 

Recent testing by GM of the truck bed regarding air flow, revealed an interesting piece of data that could stop truck arguments cold.

According to their aerodynamic engineer, leaving the tailgate up is more efficient than leaving it in a lowered position.

It seems that with the tailgate up, the air flowing over the cab falls downward against the back of the cab, pushing the truck forward. With the tailgate lowered that air escapes and doesn’t add any benefit.

They also advised against nets covering the back of the truck.

Replacing the tailgate with an aftermarket net is worse than having no tailgate at all . . . According to their engineers it is equal to a boat dragging a solid object and fishing net through water, the net is going to require more muscle.

 

Sorry but you're only 4 years late

 

Linky to article and wind tunnel pics:
http://truckingtimes.com/articles/pickup-truck-tailgate-up-or-down-aerodynamics-tested

 

Actually GM is late, the testing was done on the 2014 Sierra models and this was based on their findings. But the studies were a little more in depth than previous studies.

The Sierra spent more development time in a wind tunnel than any GMC pickup for achieving better fuel economy.

Tonneau covers for the bed help smooth airflow over the truck, soft covers are more beneficial than hard covers because they form to how the air wants to flow. Running boards can also help air flow smoothly down the truck’s sides.

Round, tube-style running boards can provide a minor improvement to the truck’s drag coefficient, while “Fully integrated, flush-mount running boards are even better.”

http://media.gm.com/content/media/us/en/gm/news.detail.html/content/Pages/news/us/en/2013/May/0516-gmc-pickup-aero.html