 FACT: Firefighters are seen extinguishing a vehicle fire outdoors  with a carbon dioxide fire extinguisher. These types of fire  extinguishers would be ineffective on a car fire as they work by  depriving the fire of oxygen. Carbon dioxide quickly disperses  outdoors and the fire would have its oxygen back in no time.  Firefighters use dry chemical extinguishers on minor car fires and  hose lines on larger ones.