Well, I was matching up the GM Precept with the template. At first glance it looks like it's way off...not even approaching the 50% mark. But how come it's one of the most aerodynamic cars on the planet (Cd = 0.174)...which still looks like a car, can fit four people comfortably, and looks like it can be mass produced? Note that it only uses half wheel covers, and non-dished wheels.
I changed Aerohead's spherical nose to a 1.36:1 ellipsoid two years ago. Far short of the 2.5:1 ellipse that pre-war research shows. Sharks and boxfish have tapered noses. It follows the Precept very closely.
I tried many ellipses at the rear and it didn't conform to any. Next, I lined up the rear half of the template and started shrinking it. The drawing is exactly 1/2 scale. I was surprised, and elated. So the template doesn't just work at full scale. Again, my hat is off to Aerohead
edit: Kachi22i scaled down the template may 24, 2013...but you DON"T scale down your success
I believe I know why it works on the Precept, and not so much on the Porsche 911.