The term registered owner is usually used in instances of title

Title (property)

Title is a legal term for a bundle of rights in a piece of property in which a party may own either a legal interest or an equitable interest. The rights in the bundle may be separated and held by different parties. It may also refer to a formal document that serves as evidence of ownership...

 of a vehicle (such as an automobile) to refer to the person who has right of possession of the vehicle, as opposed to the party that has right of property. The party that has right of property is referred to as a lienholder, and in the event the registered owner fails to pay off the lien according to the agreed-to terms, the lienholder has the right to invoke repossession

Repossession

Repossession is generally used to refer to a financial institution taking back an object that was either used as collateral or rented or leased in a transaction. Repossession is a "self-help" type of action in which the party having right of ownership of the property in question takes the property...

of the vehicle.