Each buyer gets one bid
Each buyer gets one bid on your car, and it can’t go down. A bid a buyer places by hand is final. A bid their prices made the moment you listed can be replaced once by hand, with a bigger amount or an earlier pickup time, never a smaller amount or a later time. A bid that went up is marked Raised on your board.
A buyer can take their bid back
A buyer can withdraw their bid at any time before you take it. It leaves your board without a message to you, and that buyer can’t bid on your car again. If you put the car back on the board later, they can bid on it again, and that bid can be any amount.
Bids last a week
Each bid shows the date it is good until, a week after it was made. A bid that runs out leaves your board, so any bid you see there is one you can take.
At pickup
Bids are for the car as you described it. If the car is as described, the buyer is expected to pay the full bid. If it isn’t, the buyer can change or take back their bid at pickup, and you are free to say no. Can the buyer pay me less than their bid? says what to do.