Step 1: Get inspired!
I found this picture which served as my inspiration.
Step 2: Replicate the design.
For sizing purpose, I set the grid at 2:1 and uploaded a high resolution side photo of a Chevrolet Cruze. I resized the photo of the Cruze at 28 inches, which gave a scale of 54 real world inches, which is the measured height of the Cruze from the GM website. Overlaying my pattern on the scaled photo allowed me to adjust the size as needed and allow for the split in the logo for the door.