It is a stroke of brilliance that Yubaba, the witch who oversees the spirit bath house, captures part of Chihiro's name, leaving only the first written character, "Sen." At first it feels like a theft, a loss. The girl has been robbed of her identity, and we see Yubaba as a villain as a result. Yet what has really happened is not a loss, but a liberation. "Sen," the true identity of the girl, has become unleashed, free to stretch and grow and learn.
This persona is far more interesting, courageous and dedicated and hard-working. Where "Chihiro" would lie down in the back seat and passively allow life to drive her away, "Sen" takes command of her situation, stands tall, asks questions, demands answers, and works tirelessly for the sake of others.
The scene of Sen in the ghost train has often been described by Miyazaki as the true dramatic climax to the movie. It shows the full emergence of the girl's true self, her true metamorphosis. Compare this moment to that opening scene in the family car, and you'll see what I mean.
For Japanese audiences, Miyazaki is offering a critique of contemporary society, urging the modern Westernized consumer society to sit up, wake up, and regain their connections to their vast cultural heritage. The path to the future lies in the mythic past, not in the Disneyland-esque facade.
Get off the couch. Turn off the idiot box. Remember who you truly are. Reconnect with your roots and with the true self that lies buried within.