[Buzz]

I almost always use the full harness, but that day I was headed to the tennis club literally a 10 minute drive from home. A classic example of stuff happening precisely when you figure that it won't.
Armchair forensics investigators and beer tasters here speculate that my head missed the roll bar because my upper body was out of position and had I been strapped in place it may have been worse. I think there may be some merit to that. In my normal driving position, my head can easily touch both the roll bar and the forward brace. Either way, it was pure luck and nothing to base harness use on.