every object not belted into a seat belt or something stronger becomes a missile when you get involved in a collision. Make sure that that 5 to 10 pound steel cylinder cannot whack you in the head when it goes air-borne. The front or back dash is flat out. I carry my 5 pounder on the floor in front passenger side and let my passengers deal with it. Of course I rarely carry any passengers. Figure, in a rear end collision, whatever is on your dash will be in your lap or face depending upon the force of the collision. In a head-on, anything in the backseat will be in your back or the back or your head. The stuff on the floor will at worst crush your feet. If you hit something with enough force to worry about that stuff on the front floor will be going through the fire-wall, hitting the engine as it is thrust through the firewall back at you while you helplessly hang on the shoulder harness pinned in place. Most likely your knees and femurs will be crushed as the dashboard tries to mate with the seat you are in. The fire-extinguisher rattling around at your feet will be the least of your concerns. OTH if you hang it conveniently on the frame piece by your left ear then it will definately go air-borne on a much smaller collision and crush your skull.<br><br>YMMV