Seeing as the sides of the car are just as important as the top and bottom for low drag, I've decided to start cleaning them up, starting with the windows.
From this picture, you can see that the window glass isn't flush with the outer edges of the doorframe.
My plan is to get some clear plastic sheet onto the door frame to smooth out the airflow and hopefully reduce the size of the wake. I'm also looking into replacing the mirrors with F1-style, low profile mirrors, once I can find the universal kind that bolts on your doors for a relatively low price. I've also started thinking about making some side skirts and shaping them into wheel fairings.
But first, I'll be cleaning up the glass. My left rear window doesn't roll down, so I'll start by sealing those up. I might figure out a way to remove a section of plastic as needed to allow the air to flow through the other windows when open, but that'll take some thinking and designing. Suggestions are more than welcome.
More images and info to come.