[ERTW]

I came across this and thought it interesting:

From: http://www.sae.org/mags/aei/12384

Engineers primarily used CFD for design, and wind tunnels for validating the Model S sedan.

The result is a full-size electric sedan with a drag coefficient of 0.24.”

http://www.youtube.com/watch?feature...&v=xPSZ52GDLt8

[...]

Tesla used the traditional process of optimizing the overall shape of the vehicle followed by optimizing the individual details.

Front:

[...] Exa consultants did a parametric study of changing the shape of the headlights and the area around the headlights with the goal of turning the air sharply so it adheres closely to the sides of the vehicle.

Wheels:

[...] “The wheels generate up to 20% of the drag on the vehicle so airflow around the front wheels is critical,” Palin said. “One of the objectives with the Model S was to minimize the airflow around the front wheels and to line up the airflow so it hits the front wheels head on. We needed to avoid air hitting at an angle, as often the side of the tire acts like a bucket that catches the air, producing significant drag.

Windshield/A pillars:

[...] Aerodynamicists used parametric analysis to optimize the curvature of the A and C pillars to minimize vortex formation. The side glass inset was minimized and the B pillar was eliminated entirely to further minimize drag.

Progress & validation:

[...] “early design concepts of the Model S was 0.32,” Palin said. “The major shape changes reduced the drag to 0.27, and the smaller changes provided further improvement to 0.24. These numbers were validated with wind tunnel testing "

Full article: http://www.sae.org/mags/aei/12384