Chris, start here: Aerodynamics For Racing and Performance Cars Hp1267 by Forbes Aird ($45~50)
A little hard to find but well worth it!
For more info and math:
Race Car Aerodynamics: Designing for Speed (Engineering and Performance) by Joseph Katz ($20~25)
or
Competition Car Aerodynamics: A Practical Handbook by Simon McBeath ($30)
For even more info and even more math:
Aerodynamics of Road Vehicles: From Fluid Mechanics to Vehicle Engineering ([Proceedings] / SAE) [Hardcover]
Wolf-Heinrich Hucho (Editor) ($100)
All available at Amazon.
They all "mention" frontal area - but oh well!