I do know that I can sleep in that trunk... used to have one.
When I looked at the pic, I wanted to make sure to pay close attention to the gentle slope of the roof line, which appears to be training airflow in a downward arc toward the deck lid.
While I don't think it's TOO bad, I do believe that rear window adds significant wake area, somewhat comparable to that which is created at the rear of the car's deck lid.
I think "fixing" the flow there at the window area could lessen the rear drag by at least 30%. No expert, so input is necessary here. (Phil?!?)
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