Some threads here recently have, at least by implication, suggested that understanding car aero requires a high IQ - ie it is a hard topic.
I think that has been encouraged by some posters here who - either through intent or otherwise - choose to write about car aero in really obscure language. Others quote complex tech papers. I don't mind the latter, but I fear for many it makes the subject appear even harder.
I honestly don't think car aero is hard at all. As with any area of car technology, it's of course possible to delve into the subject at very difficult levels, but it's also quite possible to know enough to gain really good modification results - and to recognise when BS is being posted.
And there is a car aero book that is quite accessible, factually excellent and well written. It's also very cheap in earlier editions.
It's
Road Vehicle Aerodynamic Design by RH Barnard.
Abe Books has copies from about US$6 plus postage.
The book doesn't over-simplify but at the same time isn't complex for the sake of being complex - a good middle line is walked.
This is an example of the writing:
I can immediately see that this addresses no less than three misconceptions that have occurred in discussion on this group in the last few weeks!
I am not sure why the book isn't often quoted here.