A battery operated Carbon Monoxide Detector wouldn't do anything to the vehicle's wiring system.

A 1.9 litre Klean Kanteen of boiling water, will contain approximately 798KJ of heat energy. You can boil the water outside the vehicle with a propane stove or fire. Assuming the Klean Canteen is partially insulated i.e. a neoprene insulated cover etc, and the water bottle releases the heat over 30 minutes before getting cold, this will average approx a 400W space heater for 30 minutes. This will of course provide plenty of liquids for hydration also throughout the night. A lb Coleman Propane bottle/stove and high efficiency kettle would bring to boil around 30-40 litres of water. If adequate ventilation is provided then a Propane or Butane/propane mix Lantern might keep a vehicle warm throughout the night. Vehicles are notorious for being poorly insulated as with any metal box sitting in the snow.

http://www.coleman.com/coleman/colemanco...1010&brand=

Along with a sleeping bag such as a British Army 58 Pattern, I also will take along some British Army Bivi Trousers and Jacket as it can be quite chilly answering the call of nature in the middle of the night especially with the temperatures getting down to -15C to -20C recently.

BTW would anyone consider sleeping outside the vehicle using a self inflating mat and Goretex bivi bag. Getting some sleep is always a lot easier lying stretched out rather than in a reclined vehicle seat even after attempting to keep the vehicle interior warm.

Anyone tried this?

It is combustion, wouldn't CO be a concern with it?

http://www.survivaltopics.com/survival/how-to-make-a-survival-heater-for-your-car/

This is where having an SUV comes in handy. If I fold the back seats flat I've got a bit over 6' of flat area to lay on. With an air mattress and a sleeping bag it's a perfect place to catch a few winks.

While not directly heating the vehicle, the hand, toe and body warmers work pretty darn well and last for quite a while. I always carry a good assortment of them in the winter vehicle kit.

Although I keep blankets, Heatsheets and a sleeping bag in my car, I think I might rely on my car's heated seats. My current car has 3 levels of heat for the front seats. The highest one is pretty toasty. I don't know what current draw is but I suspect on the lowest setting I could get more than a few hours of continuous warmth, probably much more with intermitten use and the occasional running of the car engine to boost the battery. I will have to check to see if they work with the engine off, but the battery on. Combined with blankets and warm clothes I think I'd be set.

My best plan is to stay home. I'm now old enough and secure enough to refuse to drive in bad weather. My days of driving through blizzards for work are over.

You are absolutely correct, but now your life might depend upon whether the battery and its connections are all functioning properly - that is adding complexity. My personal feeling is that I would rather keep it simple and tuck myself into a nice warm bag, just like I do routinely when camping in winter conditions. Simply regard the vehicle interior as a glorified tent (no flapping in the wind or collapsing under a snow load, for example). Nights when I have bivouacked in my vehicle during wintry conditions have been rather pleasant. I have never had any difficulty is sleeping soundly and arising well rested.

Just yesterday, I put in my car a soy candle that is about 48 hours of clean burn. It would be 100 times better than nothing. Plus, I think a candle would be about the biggest flame I'd want in a small enclosed space.

If I have the proper gear and clothing with me - absolutely. Provided, of course, that I don't foresee any possibility of having to move the vehicle at short notice.

But I must add that a bivy bag isn't exactly my idea of proper gear for sleeping comfortably in a blizzard....

For this thread, I have been thinking about getting stuck in a freezing environment during the winter. In such a case, I would not attempt to sleep outside, unless I could make a proper fire without wasting too much energy.