Video: Ford F150 pickup tailgate up vs. down in the wind tunnel / smoke test
 

Modern trucks are being designed with a wide, flat tailgate top ("spoiler") to promote flow reattachment and clean separation at the rear.

But a Ford engineer says even older pickup designs are more efficient with the tailgate up.

A tonneau is better, of course.

I was a little disappointed he didn't point people to EcoModder for examples of aeroshells, which are best.

https://www.youtube.com/watch?v=hxmjXitKggQ

I wish they showed it hitting the front with the tailgate down they only put the smoke from inside the bed with the tailgate down.

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Thanks for posting.

I wish they would have gave some numbers though...

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Looks like she's obstructing all the air flow. Can't watch the video; they say it's private. :/

disappointed:a possible explanation
 

Surfing the internet,I ran across a comment by a fella in,I think,Midland,Texas,who did undergraduate work at the Texas Tech aero lab.
They were working under a General Motors sponsored program which did the tonneau cover research which led to the 1/2-tonneau patent.
What struck me was his comment that the 1/2-tonneau was within 1% of drag that was achieved with the 'aeroshell.'
Since the GM patent application predates Texas Tech's SAE paper for their tonneau cover/aeroshell research,it looks like credit for the creation of the aeroshell goes to GM.
Even though Texas Tech's Ford Motor Company-sponsored SAE work mentioned the 'aeroshell',at a corporate level,not mentioning aeroshells in particular might be one of those 'not-invented-here' omissions.Only a guess.:p

I wonder if they had to remove it for copyright reasons.

You can view Ford's version of the video (non YouTube) in this Autoblog article:

Which is more fuel efficient, driving with a pickup's tailgate up or down? - Autoblog