It’s an age old conundrum among pickup truck owners: tailgate up or down?
We’re talking aerodynamics and fuel economy here, but without personal access to wind tunnels, the evidence most owners have to support their position is anecdotal, at best.
Many split the difference between form and functionality and replace the tailgate with an open net that lets the air through, but not their cargo.
GMC says that’s a bad idea.
While testing its all-new 2014 Sierra pickup truck, the automaker determined, unequivocally, that it cuts through the air more smoothly with the tailgate closed, and optimized its design to increase the effect.
Perhaps not surprisingly, it also found that using a net is actually worse than having no tailgate at all.
The company says this likely holds true for all of its pickups, not just the new model, but there are a few aftermarket add-ons that can effectively improve your MPG. Tonneau covers for the bed help clean up the air flowing over it, and properly-designed running boards can help as well.
Along with the attention spent on the rear of the trucks, the front of the new Sierra has been designed to direct the airflow out and around its tires and down to the ground to clear the nooks and crannies of its underbody.
It may still look like a box on wheels to you, but the air sees things slightly differently.