formula used for drag force?
 

Hi. I have meshed a car body and solved it in fluent. The solution got converged. I took the value of drag force and drag co-efficient from the report-forces menu. I have taken the projected area also.
Even though both the drag forces and drag co-efficients are displayed there, i liked to find the drag force with the displayed drag co-efficient using the formula Df = Cd*0.5*rho*A*V^2. But the drag force obtained is different from the drag force displayed there. why?....