Imagine driving down the expressway in the 2nd from the left lane, 2 lanes on your right. Average speed about 70 to 75 mph. Traffic is keeping up and going well. Look in the mirror for a moment, notice the cars behind you. Look back out the windshield and wait, that car is not moving. Wait, it is 10 feet away. Wait, I am going 75 mph and they aren’t moving. Wait, there is no one in front of them. Wait, I’m going to hit them, hard.