GMC says the 2014 Sierra spent more time in the wind tunnel than any before it as fuel efficiency becomes an increasingly important piece of any successful new vehicle.
The engine can be tuned, the truck can go on a diet, but tweaking the shape of a vehicle so air flows most efficiently is one way a relatively traditional shape like the pickup can gain mpgs.
The 2014 Sierra has a new air dam up front and ducts between the grille and radiator to improve air flow. But it was the testing of the bed that revealed one interesting piece of data that could stop truck arguments cold.
According to GMC's Diane Bloch, an aerodynamic engineer, leaving the tailgate up is more efficient than leaving it in a lowered position.
It seems that with the tailgate up, the air flowing over the cab falls downward and then pushes forward against the truck. With the tailgate lowered that air escapes and doesn’t add any benefit.
Bloch also advised against nets covering the back of the truck. "Replacing the tailgate with an aftermarket net is worse than having no tailgate at all," Bloch said in a statement. "Imagine dragging a solid object and a fishing net through water. The net is going to require more muscle."