As a compliment to Jeanne's post. 'carName' doesn't even sound unique. If you just came up with this to show your idea, then its okay arguably. Otherwise, introducing a surrogate key, if there are no candidates found, is a good idea. Folks prefer surrogate keys over natural, but again it depends upon case to case. Surrogate key is the only solution, in case you have no natural candidates.
subject: How to achieve One to One mapping between two tables