You should definitely mount any fire extinguisher you put in your vehicle. Having the thing rolling around is not only distracting, there's also the chance that it might roll somewhere where you can't find it when you need it. You should use a USCG approved mounting bracket for the extingsuisher. They're designed to be secure yet easy to use in stressful situations.<br><br>However, mounting a fire extinguisher in a vehicle can be a PITA. I work at a automotive testing facility, and corporate policy requires a fire extinguisher to be mounted in every test vehicle. The technicians here got so fed up with mounting brackets in test vehicles and then having to remove the brackets at the end of the vehicle's test life that they came up with a spiffy little trick.<br><br>Basically, what they do is mount the bracket to a piece of 3/4" plywood with 'handles' cut into the sides and ends of the wood. The extinguisher goes into the bracket, and an unused seatbelt goes through the slot 'handles' of the plywood. Voila, a nicely mounted fire extinguisher that won't roll where it isn't supposed to be, fly around in an accident, or hurt the resale value of your car. If you feel really ambitious, you can also mount a few mop handle-type spring clips on the plywood to hold road flares.<br><br>If my explanation is difficult to understand, just ask and I'll try and get a photo or two.<br><br>P.S. Don't zip-tie a fire extinguisher. Either to something, or the pin to the handle. It's just a bad idea.