The automap is a screen of the Cheapboy that shows every part of Phoenix core and which faction is controlling its key locations. Data has to be gathered first by visiting the different quarters of the city for them to be displayed on your automap.
You can access it using TAB or through the Cheapboy ('P') menu, the Automap screen being accessible pressing 'M'.
Keep in mind the direction you are moving through the core. The closer you are to the center the more dangerous it gets.
Note : You can create and remove a marker on the map by right clicking the Automap.