Final answer:
A driver that follows too closely behind another vehicle is called a tailgater. This term is used to describe Peter's actions when he drove too close to another car that was going the minimum speed limit.
Step-by-step explanation:
A driver who follows too closely behind another vehicle is referred to as a tailgater. This behavior is dangerous as it does not allow the tailgating driver sufficient space to stop without causing a collision if the vehicle in front has to brake suddenly. In the scenario provided, Peter becomes a tailgater when he follows too closely behind a car driven by a person he perceives as 'guilty of DWE,' or driving while elderly, because they were driving at the minimum speed limit.