I can't take credit for this, and it has it's limitations, but if you want to make a panel van or bronco or whatever auto you plan on using as a bug out vehicle resistant to small arms fire for cheap, check out "lightestnebula9" on YouTube. I'd imagine if you also put spray on insulation or...

From the new MythBusters episode, 'Coffin Punch' an improvised armor is made from "a high strength gypsum cement called FGR 95 which is filled with poly-proplene fiber. Now we've also inserted two layers of common bathroom tiles a little bit back from the front." It completely stopped 9mm, .45...