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

A vehicle subject to a lien on the title does not serve as proof of ownership for a Colorado dealer because the lien indicates that there is an encumbrance on the vehicle. In such cases, the holder of the lien has a legal claim to the vehicle until the debt secured by the lien is satisfied. This means that the dealer does not have full ownership of the vehicle; rather, ownership is shared with the lienholder.

In contrast, having a clean title, a bill of sale, and a certificate of title all serve as valid proof of ownership. A clean title demonstrates that the vehicle is fully owned without any liens, a bill of sale is a legal document that confirms the transfer of ownership from one party to another, and a certificate of title is an official document that proves who owns the vehicle. These elements are essential for establishing clear ownership in vehicle transactions.