"Grand Theft Auto 4" has a heavy gang presence with many different types of gangs. Unlike in previous versions of "GTA," you won't be able to recruit these members to your side. However, you will still have to keep a careful eye out for them, as they can easily become hostile and attack you. There are a few different ways to determine who is a gang member, including by location, vehicle and disposition.
Punch any pedestrian whom you suspect might be a gang member. If the person is a gang member, she will fire her weapon at you, and others with similar clothing will join in. A less violent way to find out is to walk into a pedestrian while holding a weapon in your hand. If the person is a gang member, she will tell you to put your gun away.
Look for specific gang vehicles. The biker gangs all ride Harleys, the Spanish Lords red-and-gold Cavalcades with a sound system that you'll hear coming and the mafia black Sentinels XS.
Go to the territory for any specific gang. For example, you can find the Russian Mafiya in Hove Beach, Firefly Island and Beachgate in the Broker area. They'll be driving either a black mafiyan Sentinel or a black Rebla. The Jamaican Posse can be found in Shottler and Beachwood City in the Broker area or Willis of the Dukes area driving green and black vehicles. The M.O.B. can be found in either the Firefly Projects of Broker or Acter in Albany, driving either a back modded Patriot or a black Landstalker with a television in it.
Go to either Cerveza Heights in Broker, South Bohan in Bohan, Alderney City in Alderney or East Holland in Algonquin to locate the Spanish Lords. They'll be driving red-and-gold vehicles in these areas. Go to Beachwood City in Broker to find the biker gang called Angels of Death M.C. They'll be driving Hellfury motorcyles and wearing biker gear. Go to the Steinway area of Dukes to find the Irish Mob, who will be driving either a green Contender or a black-and-green Oracle with a modified grill.
Go to North Holland in Algonquin to find the North Holland Hustlers. They drive either black modded Patriots or black Landstalkers with televisions in them. Go to Little Bay in Bohan to find the Albanian Mob. They'll be driving either red Futo GTs or a red Hakumai. Go to the Chinatown area of Algonquin to find the Chinese Triads. They drive either a dark blue Feroci with gold rings or an Intruder VX with a custom bumper.
Go to either Little Italy in Algonquin or Westdyke in Alderney to find the Italian Mafia. They'll be driving either a black Mafia Sentinel XS or a black PMP 600. Go to Acter in Alderney to find the Lost Brotherhood M.C., another biker gang. They drive black Zombies with red rims. Go to Alderney City to find the Korean Mob. They drive either a dark blue Presidente with black rims or a blue Sultan 3.5 Twin Turbo with gold rims.