Most people are aware of fire blankets. Usually found in kitchens, they are often the best means of extinguishing stovetop fires involving fat or oil. They do this by smothering the fire and starving it of oxygen.
A Car Fire Blanket works on the same principle, however, it is much larger.
It requires two people working together to deploy. Taking a corner each, they pull the blanket over the burning car (or other burning objects) then allow the overlapping proportion to settle to the ground, smothering the fire and starving it of oxygen. Once the fire blanket has been deployed it takes a couple of minutes to extinguish the fire.