Well, because of this (http://feedback.arma3.com/view.php?id=17821) Tempest is EXACTLY like Zamak, since its frontal armoured plates aren't implemented either. As well as buletproof glass isn't quite good at stopping bullets.
In summary - the whole vehicle is a huge dissapointment.

This needs more attention, because it makes armored Tempest truck almost useless if it can be taken down with a 5,56 rifle.