Removes a car from the model.
There are several ways a car can be removed:
Car can move out via any open-ended road or when it reaches the specified stop line, in this case CarDispose should follow the last CarMoveTo block.
Car can be removed from a model when it is located in a parking lot or at a bus stop. In this case, it is not necessary to immediately remove the car after it reaches a parking lot or a bus stop.
long count() - Returns the number of cars exited via this CarDispose block.