Re: Well, to be fair, that
 

hit the nail on the head there.

there are significant differences in pickup design: bed length is a big one; bed wall height; difference of bed height/bed wall height to cabin height; cabin shape. coming up with a conclusion that applies equally to all pickups seems a bit simplistic.

it would be like me insisting, "WAI doesn't work." (which i wouldn't insist) when clearly there are a lot of insight owners who would strongly disagree. it comes down to design differences.

arguing about tailgate up/down might be like arguing about which tastes sweeter: a gallon of lemonade with 2 tbsp of sugar in it, or 4 tbsp.

instead, all these folks should be either adding a tonneau, or dumping a whole cup of sugar in their lemonade by constructing a properly aerodynamic bed cover:

https://maxmpg.org/sitebuilder/images...38-441x315.jpg

Tailgate up, no question about it
 

The swirling air mass behind the cab of the truck is going to be there no matter what length bed you have. It is designed into truck shapes, and it's there for a specific reason: To decrease aerodynamic drag created by the tailgate. The deflection effect of that vortex sends the downward wind forces up and over the tailgate of the longest bed truck with which that particular cab was designed to work. That is to say that if you have an 8' truck bed, the cab is designed specifically to create a vortex of sufficient size and flow to redirect the airflow over the top of the tailgate that's 8' away from the cab of the truck.

For what it's worth, the Mythbusters crew talked with the manufacturer of the truck they tested, and they confirmed the recommendation to drive with the tailgate up. Why would the manufacturer tell you to do something that is going to decrease your gas mileage?

Re: Tailgate up, no question about it
 

Well, maybee for newer trucks, but you have to wonder when the car makers started testing this stuff. I don't think it started that long ago, they just needed a bed and made it work, why put money into testing just to change something else (wich would cost more money) it's a business remember. Another reaon they would tell you to leave the tailgate up; proves that they "know" what's going on, and have tested this stuff.

In conclusion, each person is going to have to test, test, test to find out what's best for them. and bed covers, especially the tappered ones would be great ( i can't use one, bummer) but not many people are going to spend the time, energy, money to get stares from other people. I would, but can't right now (job consideration)

More opinions and testing needed. lets proceed.