Algodoo

Its pretty good, but its not my idea of EMP, I mean, it doesn't stop the motors or the mechanisms not controled by thyme, I suggest you put this in the script:

e.other.collideset=127; e.other.heterocollide=false;

This, obviously, will make the entire machine spaz uncontrolably, I use it countless times in things. Its 127 so that plane on the ground doesn't get messed up.

still, simple stuff wouldn't get affected by it, like the tradictional wheeled box car.

well you could also just script a area(circle or so) to make everything in the field get affected unless it is simple. Like a real EMP (electro magnetic field bomb) doesn´t affect machine guns or simple guns only more advanced stuff like tanks, vehicles, communication Etc. so a simple thing wont get affected but motor hinges will be put on auto brake and motor = false and so