This is one of those moments where you must sacrifice realism for gameplay. Let's face it, many gamers ( such as myself) love to dick around and screw things up if presented the chance. If a tank was added for example, people would drive them into things, namely buildings. Having total realism would say that the buildings must collapse once hit with a tank. This combined with the fact that every zombie in a mile and a half range would be drawn to the sound would cause so much stress on the game that it may crash. Project zboid would be much better without op classified vehicles But zombies outside of view aren't loaded so they would just theoretically move without using much memory