For those of you who have a winter car emergency kit do you carry a sleeping bag, wool blankets, both or neither? And why?

My kit is currently undergoing reorganization. I used to carry a polyester fill sleeping bag, but I just ordered a couple of US Army wool blankets to replace it in the car. My reasons are that a sleeping bag can lose its loft if stored rolled or stuffed and may not be as warm as I expect it to be in an emergency (just learned while reading about sleeping bag care). Second, wool blankets can more easily cover multiple people (say three people in the back seat sharing warmth) then a sleeping bag which is only optimal for one person. Third wool blankets are more versitale. They can be handed out individually or folded together for one person. They can be used to put some one on fire out since they don't catch fire as easily or melt. And finally, they keep their insulation if damp or wet. Oh and they're cheaper, so I don't have to worry if they're damaged or lost as much.

Now the sleeping bag is lighter then several wool blankets (I'll end up having three in my car). But this really isn't too much of an issue since I don't plan to carry it on my back. For a single person the sleeping bag may be warmer (debatable).

Anyway, what do you guys think? Sleeping bag versus blankets for a car kit.