Is monthly private party car payments considered rental fees?

Until the vehicle is paid for, a person is basically renting the vehicle. If that person pays all but the last monthly payment and defaults, he or she has broken the contract (verbal or written) and is not entitled to any refunds or compensation. The monthly payments are rent for that vehicle, similar to renting anything else, an apartment, equipment, a moving van. The money is for the use or privilege of using the vehicle.