Are you talking about those kids doing donuts that circulated a few weeks back? That's super rare, I've lived here 20 years and never seen anything like that. Not saying that element isn't growing here, it has been, but this city is pretty dang safe.
A few weeks back? Not sure, but each video I see looks like they're new, so I'm only assuming that it's a regular occurance. To an outsider Austin looks pretty lawless on the roads.
Not that I know of, but there is a correlation between vehicle miles traveled and road deaths. Cars are big, heavy, and often move very fast. When cars collide with people, other cars, or built structures, it often results in deaths.