As shown in the figure below and in the Video, the aerodynamic drag on a truck can be reduced by the use of appropriate air deflectors. A reduction in drag coefficient from CD -0.96 to Cp -0.70 corresponds to a reduction of how many horsepower needed at a highway speed of 64 mph? p b=width=10 ft 12 ft hp 6) C = 0.70 (b) CD = 0.96