Okay the code tells me your giving them a Car ID that is already spawned, so why are you going through the hassle of creating another car?.
oh i must of done something wrong lol, i was supposed to make cmd /givecar [id] [carmodelid] so if i do /givecar 0 444 it will give id 0 a monster truck + when i went in-game and tested got server error msg -_-