Using the Cd, Power, Rolling Resistance, and MPG calculator I generated four curves for my F-150 with various iterations of aerodynamic appliances added.
The top curve is for the truck with a belly pan added which I have not done yet. The bottom curve is for the truck naked. The two middle curves are for the the Aerolid, and then the truck with the boat tail added. My real world data fits some of these data points pretty closely. I just have not been able to gather data under conditions that match my inputs in every instance.