How many of those accident-free miles were in uncontrolled conditions? How many of them were negotiating traffic in a rainstorm, or unplanned detours around construction, or getting boxed in by semis on the interstate, or dealing with people maybe or maybe not about to jump across from the median, or anything near the sort of calamitous and hard to manage situations typically leading to human accidents or fatality?

The Google car is brilliant but from what I understand "quite close" is stretching it.