Water does have a higher specific heat capacity i.e. the calorie per degree gram is higher than ethylene glycol. But as has been noted water vaporizes to steam on a hot surface thus reducing the ability of heat to transfer from hot metal. You can raise the total pressure; use a mixture of water and ethylene glychol; or use both higher pressure and a mixture to raise this limit to heat transfer.
Ever wonder why noone uses pure ethylene glychol as a coolant or even oil. It is because the specific heat capacity of glychol or oil is about a third that of water. Even though its boiling point would be higher the heat transfer surfaces would have to increased to get the heat from the engine hot spots; to the radiator; and then out to the air.