I carry two
Element 50 fire extinguishers. They're a pretty amazing piece of technology. Each is about a foot long, about an inch in diameter, weighs ~9.6oz, and is estimated to pack the A-B-C-K fire suppression capability of 5 5lb bottle extinguishers. So 2 would supposedly be equivalent to roughly ~"50lbs extinguisher" on a wheeled dolly weighing ~170lbs. If those numbers are anything close to real, it's over 100x more suppression per pound than standard extinguishers at a tenth of the price for similar suppression capability. Like the more expensive Halotron extinguishers, the Element extinguishers leave no residue. Additionally, no fancy mounting is required. I stuck the included brackets to the door-side of the driver seat and near the rear hatch at the base of the D-Pillar, but you could drop them in a glove-box, a door pocket, or a seat back pocket, or add a strip of Velcro and stick it on any carpet surface - at under 10oz, they present less of a hazard than your Big Gulp in an accident. In the demo in the video below, note that the grill's gas was still **ON** when he put the fire out. Element has a bunch of other videos up on YouTube.
Full disclosure: I paid full price for my Element 50's and no compensation was provided for this review.