To successfully pass the mission, disable the drunk driver. To earn a commendation force the drunk driver to stop by stress. At the start of mission pull a quick U turn and follow the arrow to the drunk driver. Once you are close to him pull up next to him and ram him from the side. You will disable him faster by trying to push him up against a building. Remember to keep an eye on your damage meter so you don't wreck your vehicle before disabling the perp. Quickly disable him by continually ramming him until he stops driving.