Problem: The turks don't allow you to enter by car (for EU citizens) and leave by plane. Something to do with tax evasion if you sell the car (unconfirmed information).
Officially you have to leave the car on a special customs parking lot which only works Mon-Fri 9:00-16:00 (unconfirmed information).
Ataturk's hotline and our embassy don't have info on how to proceed (confirmed).
Short answer - yes, you can leave your car anywhere, just don't tell the Turkish authorities.