Yes, if the owner agrees. To sell on BeaterBoss you need to be at least 18 and either own the car or have the owner’s permission to sell it.
Before you list
Describe the car honestly, just as the owner would. Bids are for the car as you describe it, and the driver checks it at pickup. Use your own mobile number on the listing, since the texts, the codes for your board and the calls about the pickup all go to it.
The title
The title is signed by the owner, or by everyone listed as an owner on it, in the seller’s spaces. Several states say every owner on the title has to sign. If the owner can’t be there on pickup day, have the title signed and ready beforehand, the way your state allows. Your state’s page lists what a seller there has to do: find your state.
If the owner has died
What you need depends on your state, and often on whether there is a will or an estate. Ask your state’s motor vehicle agency what they need from you before you list the car.
Tell your buyer
Say in a message that you are selling the car for its owner, and ask your buyer what they need from you on pickup day.