What advantage does the "coolant" (mixture of water and ethylene glycol) have over water as a liquid to cool the car radiator?

We use coolant instead of water because when heated, water can start to accumulate the minerals that it has, and this can corrode the metal on your car. Other solution could be to use distilled water, but is will also corrode the metal of your radiator. One advantage of ethylene glycol is that prevents the corrosion in your radiator providing a protective coating to the metals.