Thanks for the input!
Yeah the model is fairly imprecise. The top has a rectangular cross section rather than trapezoidal, the edges aren't curved, there are no mirrors, etc. I was just using the model to help visualize the mods I'm going to make.
Thanks for digging up the blueprints for me. Yeah the roof transition doesn't look too terrible. The idea of the top for me was about transitioning into the boat tail better. The images earlier showing the template lined up with the top vs lined up 2in over the roof were to show the difference in how much each reduces the wake area.
So the roof transition is no Prius, but it's not nearly as bad as in the model. I figured that smoothing out that transition would just be more of a fringe benefit of an aerodynamic top, whereas the transition into the boat tail would be the main benefit. If I weren't going to put a boat tail on, I would definitely not put a top on it.
Those blueprints really show how so many under-body parts stick out into airflow and can cause turbulence, as well as how the nose directs airflow underneath the car/at the ground. The first aeromods I'd make would definitely be a nose extension, full bellypan, and diffuser. A boat tail and aerodynamic top would come later on. I'm pretty sure I want to do the boat tail, as I would probably see the greatest benefit from it, and I'm fairly certain that an aerodynamic top would help the boat tail work better, but if this isn't the case then I'll just stick with a normal boat tail.
What are your thoughts on this?