Which liquid cools faster in a car, water or antifreeze?

At engine operating temperatures 50/50 antifreeze is about 85% as effective at carrying heat as pure water is. In practical terms that is identical. As the next to the last table shows, a 14% flow difference makes up for the gap.

Water adsorbs heat faster inside the engine and the cooling tubes and fins get rid of the heat from water quicker. Race cars don't use antifreeze for that reason.

If you can't possibly buy that water is the most efficient coolant go to Stewart Water Pumps and read what they say is the most efficient coolant.

The person below has a long winded article that doesn't answer your question.

A 50/50 mix of Antifreeze and Water is Best for proper cooling.

Pure water is far better, but you need to make sure that it is pure water, buy at least de-ionised, or preferably distilled water, and you'll also need to add a cooling system conditioner to help lubricate and protect your water pump. Oh, and when it gets to winter, you'll need to keep your car in a garage or something to keep it away from freezing temperatures!

@ Jesse: Yes, of course, salts are drawn from pure aluminium, why didn't I think of that! Besides, most the internals where the coolant runs are coated steel, or rubber. Don't spurt crap when you don't know what you're talking about, it makes things more complicated for the person asking the question.

Once you consider all of the requirements, a combination works best. Liquid water may have advantages, but its not worth cracking a head or an engine block. FYI http://www.redlineoil.com/Products.aspx?pcid=10

Water, but DO NOT use distilled water!!! Distilled water causes aluminum parts to corrode faster because the salts are drawn from the metal.

50/50. Water alone will make rust.

here is a good article to answer your question

http://www.arrowheadradiator.com/coolant_&_radiato...