A player might want to give some "in-game" cash to another player while in the same vehicle.
An example of how to give cash to someone while in the same vehicle could be like pressing Y ---> Select player's name (he/she must be in your vehicle)
---> amount of cash that the sender wants to transfer (from wallet or bank) ---> pressing the button "Enter" or clicking on the bar option "Send cash" and the player in your vehicle has received your money.