One of Ford’s top designers, a woman whom Autoweek once called “one of the top ten secret people who will change your world,” gave a simple but enlightening peek into the design process at Fortune’s Most Powerful Women’s conference in Hong Kong today.

Chelsia Lau is the chief designer of the global advanced studio at Ford in Shanghai. Her bonafides: she led the popular Ford Explorer SportTrac concepts; she’s designed at Ford since the early ’90s; favorite cars are the GT 40 and Mustang.

Lau gave a 10-minute primer on design, turning a sketch of an ordinary looking S.U.V. into the kind of hip-looking truck you see on the road. She made small changes step-by-step.”You know something’s off but don’t know why,” she said.

The first move: enlarge the wheels. Big wheels have better aesthetics.

Then she expands the wheelbase, making the truck longer. “Which also increases the cabin space.” Win-win.

Last, she adjusts the “body ratio,” or the length of the door compared to the side window. In the ‘before’ picture, their sizes are clunkily analogous.

She shortened the length of the glass, giving it a slick, brawny looking profile and turning the previously clunky S.U.V. into something resembling …a Ford Edge.

“Millimeters matter in car design,” she said and proved it in a few quick sketches.