I have not been to any autocross track events, and non of the drag events I have been to require one, however, Every single dirt track event that I have ever been at requires the use of a hans device. If I were to start autocrossing or breaking 12s in a straight line I would definatly have to get one. Yes it cost about 1k give or take, but really is your life worth less than that? I love to race, and build fast cars. The older I get the more I think that just jumping in a car and driving it past the limit is a bad idea.