What I would do is use ajax to control the list of cars that are available. It would be possible to "push" information when a user selects a car.
I think in database you can maintain field for Isselected which contain Boolean value. If user select that car update database with value true. When load the drop down menu select cars which Isselected =false.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.