This is all purest speculation of course.
Regards Luke -- #include witty_sig.h
No one seems to have commented on the fact that propane cannisters make very bad bombs. The steel casing is extremely thick and you have to leave it to burn for a long time before it explodes.
If the plan was to set fire to the car and then wait for the propane to go up, or even just to fill the car and light a match, that was only ever marginally likely to work.