This is from the Australian Jeep Offroad forum and I'm passing it on because it underlines the danger of stopping for any time when there's dry grass under your truck's hot catalytic converter, and/or other parts of the exhaust. The unfortunate driver had stopped in a paddock of bonnet-height grass including spinifex on the family property near Canberra and smelled smoke … it apparently took only about 15 seconds to go from smell to raging fire. You can see the full item here. One person responded with this advice:
"Once you realise you are on fire there is so much grass fuel built up that the fire builds quickly and intensely. BCE extinguishers need to be shaken occasionally to loosen the powder or you waste half of the propellant without the chemical. They need to be upright, pointing at the fire. Pretty hard to do unless you have over 16 inches of clearance at the sill to aim at the exhaust with extinguisher upright. A piece of hose a few feet long attached to the end of the extinguisher can be a life saver. Just because the flames are out doesn't mean the fire is done, the resin on the cat can still self-ignite without warning."