The circularity of this song is an aching one. The fast car is a means to an end. It's part of a dream to escape the doomed life in which she finds herself in. She has a father who drinks all day and she does everything for him. She just wants to live for herself. So she leaves with someone else and has so much faith that things will turn out. After a while, she's the only one working and he falls into drinking. She becomes the caretaker once again and the dreams never came true. Like I said, the fast car was a symbol... and it remains as such.