It's second gen, later 2000 model. Put some shit between those doors and you should have good armor. Run all of them over.
Like everyone else said, Bars over the windows and phone books or plywood and plexiglass in the doors.
Im in agreement with Prime the need for armour isn't going to needed. I would consider working something out for the windows as a complete last resort. Ive seen rail system setups for cars that will close wide windows off with metal luvered sliders. It would be noticable from a distance, and wouldnt add weight. I mean if a window did get broke and you were stuck in a place, it would be possible for a zed to get in. So having a fall back would be nice, but you shouldnt get stuck in that situation anyways, the keep to survival will be planning ahead. Not planning for worst case.
For godsakes get ride of the turret ak.