You can try to impose a variable with a timer on the vehicle when the player leaves the car. And also, if someone got into this car, clear this timer. Source:
https://wiki.rage.mp/index.php?title=PlayerEnterVehicle
https://wiki.rage.mp/index.php?title=PlayerExitVehicle
https://wiki.rage.mp/index.php?title=Entity::setVariable
https://wiki.rage.mp/index.php?title=Vehicle::destroy