[Stacked terrain and throwing terrain]

Perfectly concise. Thank you!

[Stacked terrain and throwing terrain]

I have tried searching to find any thread regarding this topic. If there is one, please refer me to the thread. 

If a car (or water tank from the apartment building terrain) is placed on building big enough to have 2 characters fight on top of. Can the car be thrown (assuming any/ all throw powers and acceptable distances) at either character?  Further if one character is on the building and the other is not (again, assuming any/ all throw powers and acceptable distances) can either character throw at the other?