Originally Posted by 05SuperDiesel
Tailgate down driving has been proved time and again to DECREASE fuel economy. Tailgate down has worse aerodynamics and more drag, counter intuitive i know.
Regards, Azam.
They just did this test on the cable show Mythbusters...the truck with the tailgate up went about 30 miles further on the same amount of fuel. It has to do with aerodynamics behind the cab. interesting stuff.