Which of the following is not considered proof of ownership for a motor vehicle in Colorado?

The signed Monroney Label is primarily used for indicating a vehicle's manufacturer’s suggested retail price (MSRP) and other pertinent information, such as fuel economy and safety ratings. While it provides valuable information about the vehicle, it does not serve as a legal document that proves ownership of the vehicle. In contrast, a properly assigned title, whether from Colorado or out-of-state, is a key legal document that transfers ownership, while the Manufacturer's Certificate of Origin (MCO) serves a similar purpose for new vehicles. Therefore, the signed Monroney Label lacks the legal authority and requisite details needed to establish ownership, making it the correct answer in the context of proving ownership for a motor vehicle in Colorado.