You have correctly identified the central question in this poem. Do we control our cars or do they control us? But really, the question is about more than cars -- it is about whether we control our material possessions or whether they control us.
Many people (mostly intellectuals) would argue that we are controlled by our possessions. This has been going on at least since Henry David Thoreau posed a similar question in "Walden" around 150 years ago.
People who make this argument would say that we spend our whole lives working in order to get things that we really don't need. They would say that we are slaves to our cell phones, etc.
But you have to decide which argument resonates with you more. Do our material posessions help us or do they make us slaves to them?
south bound on the free way discuses a major topic "do we control cars or they control us?" the poet made us think what if a tourist from "orbit ville" came to our earth.
I think that we r the brains cuz we drive them they cant work without us although they play a big role in our lives