svrwthr, the water bottle(s) wouldn't necessarily be frozen if they are kept in the car with you. You'll have the heat on as you're driving the car which will help them thaw.
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As for the horn honking, you're right in that snow will dampen the sound. But, it won't use up much juice to use the horn occasionally and if your car is somewhat hidden in a ditch or something, it could be a great help in locating you.

Why is the City Sub contracting out the sidewalks. Shame on you Todds Grounds keeping for taking a union brothers job. You should know all about that Mr.GM UAW. I wonder what your union buddies would think.

So what the heck is a bottle of frozen water gonna do for you? Ya it may be fine in warmer months but in winter and frozen? Leave it in the trunk with the jumper cables. A person is better off keeping 2 steal cans in their vehicle. 1 clean and 1 for the candle. The candle I think is funny though, what a better way to get someones attention and keeping warm by having your vehicle catch on fire. But anyways on with the idea. Use the candle safely for some minor heat to you extremities and the other clean one for melting snow which will melt easier than that frozen plastic bottle of water. Don't eat the snow. Drink the melted snow only.

Remember heat gets to your inner system faster through your hands and feet. Keep them warm and dry at all times. It's a proven fact. Buy some small chemical hand warmers will be better than candles. You can always use your heater to melt snow in the can much safer than the candle as long as you are not running your engine for too long and have proper ventilation.

btw honking your horn in a snow storm is not going to do anything. You can do it to feel better but in a snow storm the honking horn is not going to do much since the snow acts as a sound dampener and barrier for sound to travel very far. Go outside in a snow storm and listen once if you don't believe me. It's eerily quiet in a heavy snow fall. That is because the multitude of snow flakes are blocking sound from traveling. But honk as much as you want. Maybe your battery will die faster.

I know they're just trying to prepare people for the inevitable... it's wisconsin winter: NO BRAINER!!!!

waaaaaaaaaaaaaaaaa

if you use a coffee Can (metal) and a large candle that fits in can it will keep you warm enough also along with the things mentioned in article for a good amount of time.

Starting the car and letting it run for a bit periodically will help keep the battery up. You'll probably have to let it run for more than 10 minutes if you plan to have much heat coming out of the vents. If you are stranded in a ditch or some place not easily seen from the road, honk your horn (3 short blasts at a time) periodically. This will help rescuers find you.
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A roll of toilet paper in a plastic bag is probably a wise choice.
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Jumper cables are a must in this area. You can't just rely on someone else having them if you need a jump.
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While a battery operated radio is better than none at all, consider investing in a crank powered radio. For any items you store that require batteries, either keep the batteries separate or reverse them in the item. Otherwise they might accidentally switch on and drain the power. Change the batteries periodically to keep them fresh.
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Keep your emergency supplies in the car with you, not in the trunk, if you can swing it. If you're in an accident and stranded in a ditch, you might not be able to get out and open the trunk. Use a duffel bag or backpack for storing the items. Things like jumper cables can obviously go in the trunk. But, anything you might need to keep you alive if you're stranded should be in the car with you.
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Consider adding a deck of cards, paperback book, or some other activity to keep you occupied. If there's a chance you'll be stranded with kids, be sure to pack things for them to do as well.

Food: Canned goods are a poor choice for a car disaster kit. This time of year, you're going to be eating a ravioli popsicle, unless you also pack some way to cook the food. A better choice would be some protein bars, granola bars, that sort of stuff. Think along the lines of food you can eat straight from the package, that don't require any prep at all. Also give thought to the temperature extremes we see around here. You don't want anything that will be adversely affected by high heat or freezing temps.
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You'll want a couple blankets to add to the additional cold weather gear. Mittens are better than gloves at retaining warmth. A space blanket (one of those ultra thin and shiny blankets) is a wise choice. But, don't just leave it in the original package. Take it out and refold it before storing it in the car. Otherwise, it can and will easily tear along the original fold lines and be worthless to you when you need it.
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Consider adding a deck of cards, paperback book, or some other activity to keep you occupied. If there's a chance you'll be stranded with kids, be sure to pack things for them to do as well.

A few comments about the guidelines listed above, taken from the American Red Cross. And, I'll preface my comments by saying that while I'm not necessarily a recognized expert, I have studied emergency preparedness for the last 20+ years and know a little bit about this sort of thing.
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The gallon of water per day, per adult guideline is to encompass drinking, food prep, and limited hygiene. That's actually a pretty low estimate as things go. But, for a car disaster kit, 2-3 gallons should suffice. Don't store the water in milk jugs! They are not meant for long term storage. Use old 2L soda bottles. Make sure you don't fill them all the way to the top. Leave a couple of inches for expansion when they freeze. Make sure to change the water a couple times a year so it doesn't get stagnant.