http://en.wikipedia.org/wiki/List_of_motor_vehicle_deaths_in...
Murder, aggravated assault, rape, robbery, etc. are all down across the board, in some cases by more than 50% in 20 years:
http://www.fbi.gov/about-us/cjis/ucr/crime-in-the-u.s/2012/c...
There are always some subjective decisions on data reporting, but that's much more prevalent in data comparisons between countries rather than over time within a single country. The FBI has been very consistent in their reporting.