If you really want to prove this one way or another, get two pans, put equal amounts or water in one and antifreeze in the other, put a thermometer in each one, and throw them on the stove at the same setting.
Check the thermometers every minute or so, and record the results.
Also, check the rules at your local track. Notice that they specify you are only allowed pure water in your cooling system? Think they would get away with that if racing your car on water alone could cause damage?
Racefiend, jimi and IJ are all correct - well, mostly anyhow. There are things that you can add to water to make it cool better... Antifreeze just isn't one of them. The subject of what you could add to your water to help is a totally different thread, though.