Aerodynamic Coefficients
C_D: 0.255 +/- 0.003
C_L: -0.215 +/- 0.009

Results: As expected the bed cover reduced the drag of the truck. The bed cover keeps the fast moving air of the free stream from intruding into the bed area and hitting both the bed bottom and the tailgate. The physical bed cover decreases drag more effeciently than the air bubble “cover” caused by a tailgate and spoiler because of the solid state of the physical cover. While the air bubble provides sufficient drag reduction, its ability to completely deny free stream air access to the bed region is limited.

The image to the side is a picture of the truck with the bed cover addition. The graph below shows the convergence of the drag coefficient as Reynolds number is increased.