We shall see

30k miles on my 15' 4x4 dcab. since day 1 I've checked the gas mileage every tank and it's been 19.8 -21.6. Today I installed an Extang Trifecta. Any guesses as to any mpg improvement?

 

Loss

 

I have an extang solid fold on my Tacoma. Can't tell any difference in mpg with or without the cover.

 

Mythbusters proved that they don't improve mileage in one of their episodes. The mesh tailgate was the only thing proven to improve mileage (5% increase).

 

As I remember it the mesh gate reduced mileage. The solid gate produced a fairly stable high pressure area from the top of the cab to the top of the tailgate that allowed air to smoothly over the truck. The mesh gate created turbulence in the bed area and disrupted airflow over the truck.

 

http://mythresults.com/episode64

(Bottom of the page)

Your right about the air vortex. The worst scenario was having the tailgate down, as this deleted the air bubble in the bed. If I remember correctly, this actually made mileage slightly worse. But the mesh was the only thing that actually improved mileage.

 

Zero to none