Raising the speed limit from 70 to 75 mph will result in speed increase of just seven percent. However, a 3,000 lb. vehicle hitting a solid object at 70 mph will experience a crash force of 491,744 lbs. but that same vehicle striking a solid object at 75 mph will experience a crash force of 564,502 lbs., an increase of 14 percent.
Add to that, the tendency of many drivers to drive 5 mph over the speed limit and the crash forces rise to 642,277 lbs., an increase of 30 percent. Read more: Bill to increase speed limit heads to Senate floor