A fairing apparatus for reducing aerodynamic drag of a tanker in a freestream, and including a fairing body with a roof section, and left and right side sections connected to and extending below the roof section. Fasteners, for example, mount the fairing body on a cab of the tanker so that the roof, left, and right side sections extend from the roof, left and right side surfaces, respectively, of the cab towards a cylindrical tank carried behind the cab to reduce the gap between the cab and the tank and impede cross-flow therethrough, and the fairing surfaces of the roof, left, and right side sections are angled and preferably curvilinearly contoured to redirect airflow from the top and side surfaces of the cab to the curvilinearly contoured top and side surfaces of the tank to compensate for a profile mismatch between the cab and the taller and / or wider tank.