Ok, finally someone has posted the Car Life article online. Good, I don't have to scan mine.

Read it here instead of going off my memory of it:

http://www.rotaryeng.net/Car-Life-all.pdf

IMHO, it gives you some insight on the 68 S/S Dart vs Cuda debate too. The Cuda is a fastback like the GTO and the Dart is a sedan like the Camaro. But of course this does not give any insight to aero drag issue.