trust in yourself
the only problem with these types of heaters is that they do not last very long. One YouTube video timed it to about 3-5 minutes of heat using the 70% alcohol and even less with the 50% alcohol....i prefer the versatile hobo stove....
They burn for longer than just 3-5 min!
Get 1 gal isopropyl alcohol at CDN Tire or Napa for about $8
Hobo stove is great, but you need to keep twigs in your car then. Picture, stranded on 401 or 402 end of January or Feb in a blizzard. The stove is Emergency, so this could help lots as well making up a stand for above it to heat up water for tea and soup.
Also I suggest making some pop can candle holders; make some barn doors on pop cans, cut emergency candle in half, put in with matches, get a cheap bit of cord or metal string and hang from the mirror.
This will keep the air warm enough for you to survive, no it will not keep the car hot, but the warmed up air is easier on the lungs and will allow you to live.
In regards to the emergency stove, I have seen others post that they use it for cooking up or heating up water, time and time again. Just keep adding in the Alcohol when cold and re-use. One fellow said it was still be used after one month of operation in this way.
I got one of these in the vehicle when travelling. Along with 3 cansiters.
Nice little unit but beware of carbon monoxide if using this in a vehicle. You have to manitain a source of fresh air. Perhaps also have a battery operated CO detector in your kit.
Read a forum where a guy put one next to his CO detector and had a 0 reading. Still crack a window (do this in my tent). The real worry for me would be Co2.
In a normal O2 environment you will get very little CO. The problem is in a closed space when the O2 levels decrease to the point where there isn't enough for a complete burn. Then you will get CO. In a ventilated room or outside you will NOT get CO so the "test" the guy was talking about was very flawed. That's one of the problems with the internet; erronous information that can kill you.