Some Questions never seem to be answered satisfactorily. For years humanity has grappled with burning issues such as “which came first, the chicken or the egg?” and “if a tree falls over in the forest and hits an import and no one is there to hear it, does it make any noise?”
Another Favorite for truck customers is whether or not the removal of the truck’s tailgate in anyway impacts fuel economy.
the truck’s raised tailgate, keeping drag behind the truck minimized.
“Putting the tailgate in the down position tends to increase turbulence and drag of the open box,” explained Jack Williams, of Ford Aero Systems Engineering. “We’ve seen drag increase as much as .5 to 1 percent. Flow-through, web-like fabric replacement tailgates tend to increase drag even more; we’ve seen increases as much as 4 to 5 percent.” In a nutshell, all of that extra drag translates into worse fuel economy for the vehicle.
Dr. Edward Fitzgerald, an aerodynamics expert and a jet engine designer with Boeing, added that the effect is actually magnified with speed increases, so that 1 percent increase in drag with the tailgate down as city speeds has much more adverse effects on fuel economy at 70-75 mph on the open road.
Contrary to another5 popular myth, pickup size doesn’t matter. Toyota engineers report that although the haven’t done any EPA testing, they speculate dropping the tailgate can actually decrease fuel economy depending on the cab and bed configuration of the pickup.
As If That Weren’t Enough…
Another concern with having the tailgate down or removed completely is the damage done to the tailgates exposed hinges and inner workings.
Judging by the numbers of tail-less trucks driving down the highway, one would assume that their owners must have figured out driving with the tailgate down gives better fuel milage. And that kind of makes sense; the wind rushes over the cab and hits the tailgate, so it ahs to slow the truck down and reduce the fuel economy, right?
But as many customers already know, modifications may be visually appealing but may not always be cost effective. At least that’s what the automotive designers find when they start placing pickup trucks in wind tunnels.
Bursting Their Bubble
According to design experts, the truck tailgate if designed to create a cushion of air in the bed that aerodynamic engineers called a “seperated bubble” (the real nerdy ones refer to it as “Locked Vortex Flow.”) Jargon aside, this invisible bubble of air actually helps deflect the faster moving wind coming over the cab so it passes over
Driving with the tailgate open has been likened by some to slamming it closed repeatedly for whatever amount of time your customers are driving down the road. The bumpier the road, the worse the abuse.
According to many of those same experts, the best way to improve a pickup’s fuel economy is to leave the tailgate up and cover the bed with a quality after market tonneau cover.
“Tonneau covers on pickup boxes reduce aerodynamic drag” said Ford’s Jack Williams. "we’ve seen reductions of about 8 to 10 percent on the F150, which means the average fuel economy improvements for the EPA city/highway cycle(test) is about 2 percent.
“The average steady-state (cruise control) fuel economy improvement at highway speeds is close to 5 percent…”
Adding a tonneau could mean an improvement in fuel mileage that is the equivalent of a free gallon of gas for every 20 gallons used.
it’s a damn parachute.
