Rockstar has abandoned the system where it was enough to briefly disappear from the cops' sight for them to almost immediately forget about what happened.
Rob Nelson, co-head of Rockstar North, said that the new mechanic is handled by the "heat" system. Information about what the police know about the hero will be displayed under the wanted level. Cops can remember his clothes or car, and then recognize the player again even after the wanted level disappears.
The mini-map will also change: police will no longer automatically appear on the radar during a chase. The player will have to monitor the environment and anticipate the cops' actions. The Focus function, which allows spotting police through walls, will help.
It might be harder, but it's fun. It will make players think more.
Vice City residents will also react more realistically to the hero's weapon.