As with all aviation - motoring comparisons, it is unfair to compare hours or miles travelled. The only fair measure is number of journeys since most accidents, when flying, occur at landing or take off. Aviation still wins but not quite so well. See "Tombstone Imperative" by Andrew Weir, its about commercial but still relevant.
I have seen quite literally hundreds of motor accidents and there have been six fatal or near fatal motorcycle accidents at the end of my road in the last eighteen years. I have only seen one GA fatality and that was in 1957 when an Auster flew into a hill near me. I was unlucky enough to see three accidents at Biggin Airshow a couple of years ago and one of those killed two very fine people but flying ancient jets is like that.