Thanks for posting these. Flow simulations are always welcome.
As you said, the accuracy isn't perfect. I wouldn't draw any conclusions about ground clearance with a stationary road and no rotating wheels, for example, because those factors could well change the outcome.
How the heck did you get SolidWorks to tell you total lift and drag? Maybe that's a new feature to SW2010? I tried to estimate drag for this model, with and without tail extension:
http://ecomodder.com/forum/showthrea...tml#post161595
But I couldn't get a CFD program simple enough for me to use, and complex enough to be confident in itself to spit out Fx and Fz.
Just as a sanity check, what does your Cd work out to for each case? That would be Fx/(.5*A*rho*Vē), with V being free-stream airspeed and rho being air density.