I agree with
@MyChoiceAlone. You need to do some more reading and studying. It's been done plenty of times without causing a fire. Of course, you need to keep the hot coals away from materials that could catch fire. The container the coals are in need to be placed on something that cannot burn, like bricks or something. It is relatively cheap and can be quick, IF IT IS DONE CORRECTLY. That's where the reading and studying comes in. If it isn't done right, there is the potential to really mess yourself up should you survive the attempt. I plan on using a well-sealed tent myself. I just think it's easier than dealing with a car. And, I also purchased a CO analyzer capable of measuring CO levels up to 10000 PPM. The lower the levels, the longer time it takes to reach unconsciousness and death, and to have to deal with all of the "uncomfortable" symptoms that CO brings on. I don't know how one can know if the level of CO is enough to produce a quick and painless death if one doesn't have a meter. You're sort of just shooting in the dark without one.