I recently ran another CFD model for as much of the car as I could realistically get Solidworks Flow Simulation to run - I've found that it has a tendency to crash on larger mesh sizes with no indication as to why it crashes. As I mentioned before, I've started doing half car models so that I can effectively double the number of cells since the car is symmetric.
Compared to my previous full car simulation, the results are pretty much identical. In the previous simulation of the full car, SW Flow Sim ended up at about 2 million fluid cells after refinement; in the half car, it also ended up at just over 2 million cells after refinement. Seeing as there's not a whole lot of difference due to the additional refinement, I would say that for this level of model detail, 2 million cells for a half car is more than enough.
The car without any aero produces a non-trivial amount of lift, and in total the full car produces approximately 400lbf downforce and 75lbf drag at 60mph in this CFD analysis. The balance of downforce is almost exactly 50-50, with a small rearward bias. And once again, the rear wing produces twice as much drag as the diffuser and front wing combined - it's interesting to note that aero package drag is on the same order of magnitude as the non-aero package drag, which is promising for active aero.