George is using valid logic. He can apply the template wherever he can, knowing that it will help, but obviously not give him full benefit. I've shown that a brick with rounded edges is ~70% worse than an ellipse, and sharp edges are worse still.
fyi, a circle has the smallest perimeter for its area - hence the lowest skin friction geometrically possible. An ellipse is the next best cross section wrt aero.
All of the details that Phil mentions are important. He's shown many times how aerodynamic basic shapes go to pot when they make a full sized prototype.
I was literally thinking of CFDing a very similar shape last week. Your car is a spitting image of the 1980's group C cars...like the Porsche 962, minus the German flag
Are drag, lift, and f/r distribution (pitching moments) a big concern for you?