I attended a lecture at the Behring Automotive Museum at Blackhawk some years ago. The speaker, as I recall, was the museum director. His talk was about the Airflow. And as I recall he pointed out that the most aerodynamic Airflow was the the DeSoto 2-door coupe. That was primarily because the spare was tucked behind the seat, rather than tacked onto the trunk lid. This gave the car the smooth rear profile that was most aerodynamic. And wind tunnel test showed that the back end shape of a car is more important than the front, when it comes to reducing wind resistance/turbulence.
As with many things, the engineers had the right idea about the Airflow, but when it came time to produce the car, the manufacturing geniuses made it much heavier than planned, which negatively affected the car's overall value (worse gas mileage). They just didn't believe the unibody type construction would work, so they added unnecessary steel reinforcement.