Which of the following is NOT proof of ownership for a motor vehicle for a Colorado dealer?

A vehicle subject to a lien on the title does not provide proof of ownership in the same way the other options do. Ownership of a motor vehicle is typically established through a clear, unencumbered title, which means that there are no claims against the vehicle, such as those from a lender or creditor. When a lien exists, it indicates that the vehicle is still under financial obligation; thus, the lienholder has a legal claim to the vehicle in the event of default on payments, preventing the seller from transferring clear title to the buyer.

In contrast, a notarized bill of sale, a certificate of title, and a dealer's invoice all serve as valid documents that demonstrate ownership. A notarized bill of sale acts as a legal record confirming the transfer of ownership. A certificate of title is the primary document that establishes ownership of a vehicle, and it shows whether there are any liens. A dealer's invoice can also function as proof of ownership, documenting the transaction and confirming that the dealer has acquired the vehicle for resale. Therefore, a vehicle with an active lien does not provide definitive proof of ownership, making this option distinct from the others listed.