Do "vented" tailgates help on 5th wheels?

Stefonius wrote:

45Ricochet wrote:

N-Trouble wrote:
Ever see the Mythbusters episode where they tested mileage on a truck with both tailgate on and off? The truck with the tailgate on got better mileage. MYTH BUSTED...

I wish they had done a test with a 13' high wall above the bed pushing all that air into the bed :W
A must have? no. More MPG most likely a toss up. Make hitching up easier? yes

Agreed. Mythbusters did not do a test with a fifth wheel attached. The airflow is vastly different in that case. I have had things sucked out of the bed with a solid gate. With my current gate (made out of steel tubes), nothing in the back of the truck moves so much as an inch as long as the fiver is hooked up. With the bed empty, it's a different story.

Your comment about items getting sucked out of the bed with a solid tailgate is exactly why you get better mileage with a tailgate in place.

Quoted from Mythbusters:
Closing the tailgate actually improves fuel efficiency because it creates a type of airflow called a separated bubble within the bed of the truck. As wind rushes over the moving truck, that bubble of slow-moving air deflects it over the raised tailgate. By guiding surrounding air over and across the bed of the truck, that vortex effect prevents added drag.

However, driving with the tailgate open eliminates the bubble effect, pulling the air toward the truck bed and creating more drag rather than deflecting the wind. Some gas-conscious pickup drivers still swear by leaving their tailgates open, but science sides with leaving it up.