(PS4) How to change things with his second account? (Rocket League)

PS I have two accounts, the second is good for two people with Split-scrin. So I have two imported car, but on one account, but as a second car I just will not use, I better throw it on your second ACC. Question: how do I throw this car on a second account, when one lobby can only be accessed through the function Split-screen? (when you go through it and choose the nickname of the character who plays with a second controller, no tabs to offer exchange)