12 layers of laminated bulletproof glass and 5 inch thick bulletproof steel!? Isn't that a bit overkill, especially if you think about the range of weapons that would've been available back then?,(reply>), 5/8 inch steel, not 5 inch.It's on the sides, roof, and floor.  In the dining room floor is a roughly 8x8-inch trapdoor to access valves for the water tank and its feed air supply.  That little trapdoor is a full inch thick, and weighs about 30 pounds.  I had to wrestle with that sucker in 1990 when the car went to Ogdensburg NY.,(reply>), It was probably just as much to protect against explosions, just having a heavy car offers some protection on its own since it makes it harder to knock over.