Cooper, K., "Pickup Truck Aerodynamics - Keep Your Tailgate Up," SAE Technical Paper 2004-01-1146, 2004, doi:10.4271/2004-01-1146.
The aerodynamic effects of the pickup truck tailgate are examined in this paper. It is shown that the removal or the lowering of the tailgate increases the aerodynamic drag of a pickup truck, increases lift by up to sixty percent and increases the yawing moment. All these changes are negative and reduce vehicle performance, albeit, only by small amounts. This finding demonstrates that the commonly seen removal of tailgates to reduce aerodynamic drag is a public misconception that should be discouraged by manufacturers and by regulators.