I learned why you gotta wear a helmet at the autocross practice today in San Diego. I was comin around a hard breaking turn, car (91 CRX) started to spin. I corrected it, and as the car whipped back into line on the track, my head wacked against the upper edge of the door. If I hadn't been wearing a helmet, my head woulda hit the window. So, for all of you who may have been curious as to why solo racing requires a helmet, that's why.