The best mixture of antifreeze and water is 50% antifreeze with 50% water. The cooling system in your car has a mixture of 6.00 L water and 6.00 L ethylene glycol (antifreeze). The molality of the solution is 17.9m. The chemical formula of ethylene glycol (antifreeze) is C2H6O2 and its density is 1.1132 g/cm3.