In general, if you are the sole owner of a car and your name is on the title, you have the legal right to possess and control the vehicle. However, if you have allowed someone else to use or possess the car for an extended period, they may have established certain rights to the vehicle, such as the right to possession or even ownership.
To protect your rights and ensure a lawful resolution, it's important to consult with legal counsel familiar with the relevant laws in your jurisdiction. They can advise you on the appropriate steps to take, such as sending a demand letter or initiating legal proceedings, to recover possession of the vehicle while minimizing potential legal complications.