I saw the container where you placed the charcoal and it looks to be small and inconspicuous. Also, the car looked pretty clean, nothing suspicious and since CO is colorless, odorless, and tasteless, the person using the method would (I assume) drift off into unconsciousness. This could potentially be a good backup method if for whatever reason or cause I am unable to go about my firearm method (such as not having the open opportunity to CTB, changes in life situations that make CTB difficult, timing, etc.).
Last but not least, ugh stupid mental health hotline being mentioned, but I guess it's obligatory in CTB related articles, videos, and news (probably a liability thing, idk).