1. the profile line -- an almost continuous, flowing smooth line from front to back that makes the side profile of our cars such a unified shape. 2. the french curve -- just below the profile line. It mimics the shape of the windows, including the rear quarter window that curves sharply downwards on our cars 3. the bottom line -- a flowing S-curve. This was also incorporated into the final design in the gentle curve at the bottom of our car between the front and rear wheels.
And lastly, the french curve combines with the bottom line to form the letter "Z".