Watch. That's all you can do.
I'm a firefighter, and unless you have SCBA (an air pack), you're risking breathing in:
- Hydrogen Cynanide
- Carbon Monoxide
- Phosgene Gas (note that ONE breath of that can kill you)
Not to mention the fact that the tires can and will explode with considerable force, the shock absorbers can and will launch like a missile, and the gas tank can and will rupture and flow burning gasoline onto the ground. Plastic burns HOT (it's just solid oil afterall) and as things POP and BOOM in a car the plastic flys around, and like napalm, it sticks to stuff and sets it on fire.
Unless you catch a car fire in the VERY VERY early stage, there's almost no stopping it. I mean like under 60 seconds from ignition.
If YOUR car catches fire, stop, get out, run IN FRONT of your car at least 75 yards and GET OUT OF TRAFFIC. Your car will provide a slight blocking of oncoming vehicles, but it's still dangerous.