I asked myself also about this question a long time (e.g. the german border is very close and as far as I know in Germany a helmet is not mandatory as long as you wear a security belt), but Austrian legislation seems to be one of the more restricted ones, at least in theory. Anyway, I would not like to drive without helmet, at least outside city limits, my head seems to attract flying stuff like a magnet.
So there was no point in further investigation for me, but I am still interested in this matter.
