There is a test given to prospective propane pump jockies.. They were reviewing the test as I was doing my daily internet run in the same room.. The instructor would read the question and then give the answer (After a pause)
The Question: What happens if you get the right porportion of propane gas and air and there is a spark? I entered at the pause with "You land 2 counties over"
The class broke up laughing.. then once they finished the instructor said "Exactly". (I got it right and I waS not even part of the class :) )
I leaned a lot of stuff I'll never use listening to those questions and answers and a couple of useful things as well.
But Not just Propane. also Gasoline, Never carry inside a CLOSED vehicle.
Diesel fuel is safer but well. I have no reason to transport that.