Well, they tried that but they took a look how other people from other states drive instead of taking a look how Iowans drive. I would look how Iowans drive then make any necessary changes tot he speed limit according to that data. Since the legislature didn't, they went by how Nebraskans, Dakotans, and Minnesotans drove and increased the speed limit based on that data.
Result: More fatalities in car accidents in Iowa.