Are public auto auction listings considered public information?

As a general matter, facts cannot be copyrighted. In other words, the fact that a particular vehicle was offered for sale at a particular auction is not something that can be protected under the laws of copyright. There are some limitations on this principle, however. First, if the collection of listings has some originality or authorship content -- as opposed to the data itself -- that authorship, or the selection and arrangement of listings, may be copyrightable. Second, if you have obtained access to the listings by your agreement to terms of use which preclude further copyright, that agreement may bind you even though the law of copyright does not apply. If in doubt, speak with an attorney before commencing your proposed business.