[aerohead]

Computer crashed while in the midst of posting.
The short story of the CR-Z is that it has the 1922 Jaray 'pumpkin seed' contour.
Starting with Hoerner's streamline body / ellipsoid drag table, @ Reynolds number = 10-million, and adding the Honda's mutilations to the 'naked' form, reconstructing the CR-Z's Cd 0.30 is pretty straight forward.
If it weren't for the main body not being boat-tailed, as is the greenhouse, by deconstructing the mutilations, it would be straight forward to reconstruct the Cd 0.13 of the 1922 car.
It would be easier with a BEV. And the necessary length would most likely be best accomplished with a one-wheeled trailer with gap-filler, and only on long road trips.
For it's length, your roof is 'perfect.'