Instructions
Rapidly change your character's direction while running down a city street. In "Grand Theft Auto IV," cars and pedestrians spawn in the direction that you're running. If you rapidly change your direction every few seconds, this will cause more cars to spawn around you than if you were running in one direction or just standing in place.
Run from one portion of the city to another. The cars and pedestrians in "Grand Theft Auto IV" will only spawn in the portion of the city you're in. If no cars are spawning in one area, use the heads-up display map in the lower left corner of the screen to run to a completely new area, which is likely to cause the game to spawn new cars along the way.
Exit to the game's main menu and then go back into the game. This will reset the game, allowing cars to spawn normally (if their failure to spawn was the result of some kind of glitch). Only do this after you have saved, however, as exiting out to the menu will cause you to lose all unsaved progress that you have completed since the last time you saved at one of your in-game safe houses.