You are correct in that aerodynamics is a very complex science, but unlike race cars bodies such as those used in NASCAR that are designed from "the get go" for the best aero advantage possible within the rules of the sanctioning body. When it comes to street cars, many of the advantages go away as aero advantages become secondary to safety, style and the bean counters (sales) in the design of street cars.. In the real world in which we drive our cars, most aero designs lose their effectiveness due to the speeds we travel. As an example the Chrysler wing cars, the Superbird and Daytona were very effective at high rates of speed required at the super speedways....the same "aero advantages" didn't come into play until speeds over 70 or so. I remember one area that a driver of a street wing car could really feel the aerodynamics ...while passing an 18 wheel. The uprights acted as rudders and stopped the pushing you get as you are completing your pass of the semi. The front end and the spoilers did give you the feel of being "planted", but again mainly at high speed. And, speaking of spoilers...a rear spoiler should never be used without a front spoiler to "equalize or balance" the aero down force of the rear spoiler.
Regarding the engineers spending a lot of time on the Challenger's hood scoops...I am not sure how much research went into the design as it is basically a direct copy of the 1970 scoop, which was blocked off and never functional. The most effective hood scoop Dodge ever had for the Challenger was the T/A scoop. Chrysler has many older reports out there on aerodynamics that are both interesting and enlightening. One of the most interesting is their wind tunnel studies of the wing cars, and there is a copy on the Wing Warriors web site.
We could go on and on regarding the subject of aerodynamics, but just want to add my two cents...