Vehicle Features/Horns

Horns are a feature that appeared in all Grand Theft Auto games. There are also sirens, reverse beeps, jingle bells, special horns and musical horns throughout the GTA games.

In 2D Universe Games
In Grand Theft Auto, Grand Theft Auto: London 1961/1969 and Grand Theft Auto 2, the player can honk the horn by pressing TAB on the PC. Police cars have sirens instead of a horn. The Ice-Cream Van has a musical jingle instead of a horn, but it serves no practical purpose.

In 3D Universe Games
In Grand Theft Auto III, Grand Theft Auto: Vice City, Grand Theft Auto: Liberty City Stories and Grand Theft Auto: Vice City Stories, the player can honk the horn by pressing H  (LSHIFT or RSHIFT in III and VC)on the PC and the Left Analog Stick on the PS2. A feature, unique to large trucks, is the reverse beep. This adds some realism, as large trucks in real life normally have those beeps. In Grand Theft Auto: San Andreas however, this feature is missing, but horns are used the same way as the other games.

From the 3D Universe games onwards, emergency vehicles may use the siren to move other vehicles out of the road, which makes it easier when doing the Vigilante, Paramedic and Firefighter side missions. Again, the ice cream van has a unique musical jingle instead of a horn, except for GTA San Andreas, where the player could honk normally if the horn button is held down. The jingle of the Mr. Whoopee is used for the purpose of selling "ice cream" for the Cherry Popper Ice Cream Factory. Uniquely to GTA San Andreas, bicycles have a bell instead of horns.

In GTA San Andreas, sometimes pedestrians will not get out of the way if the player honks at them; instead, they will show disdain.

In HD Universe Games
In Grand Theft Auto IV, the horn functions remain unchanged from the 3D Universe games. Emergency vehicles' sirens still move vehicles out of the way. There is still an ice cream van with a musical jingle in the game; it has 6 different jingles which speed up and slow down depending on the speed of the van. Reverse beeps return to the HD Universe games; most industrial trucks have them. Uniquely to the Mr. Tasty, it sounds like a "ding-a-ling" instead of "beep". In GTA IV, some cars have unique horns, not found in any other vehicle in game. Differently from the 3D Universe, boats now have horns, louder than any car horn. Railway vehicles also have horns. They can be heard randomly, or in GTA IV 's case, only during certain missions.

In Grand Theft Auto V the horns have been expanded. Car horns are more random and can be different even if the car is the same. Additionally, the player now can modify his car's horn at the Los Santos Customs. Tow Trucks have rotating lights on the top, but it makes no sound at all and serves only for realism. The Airtug has a unique siren that makes a sound of a reverse beep; oddly, it can move vehicles out of the way. There are 3 different reverse beeps on the trucks. Bicycles, again, have bells instead of horns. In the enhanced version of GTA V, some emergency vehicles have a unique siren. For example, the Ambulance siren sounds like a lower version of the Grand Theft Auto: Vice City, Grand Theft Auto: Liberty City Stories & Grand Theft Auto: Vice City Stories police siren.

Pedestrians in HD Universe games now run away from the player's vehicle if they honk at them. In GTA V, car drivers will react when someone honks at them several times, sometimes driving recklessly in the same manner as when they spot a crime. Additionally, they may stop and exit their vehicle and pursue the player in a hostile manner - or even open fire at them (if they are carrying a gun) - if provoked repeatedly.

Vehicles with Unique Horns
GTA San Andreas: GTA IV and Episodes: GTA V and GTA Online:
 * Stafford
 * Euros
 * Hotknife (Not in PC and mobile versions)
 * Patriot
 * Caddy
 * Marbelle
 * Willard
 * Forklift (shared with Airtug and Caddy)
 * Beater Vigero
 * Subway Train
 * APC
 * Nightblade
 * Hakumai''
 * Fortune
 * Slamvan
 * Tug Boat
 * Clown Van (clown horn. Can be purchased at mod shops)
 * Train (can be operated by the player in Derailed)
 * Cutter (GTA V only)
 * Cruiser
 * Endurex Race Bike
 * Space Docker (6 variations)
 * Seashark (and its variants)
 * Roosevelt and Roosevelt Valor
 * Insurgent, Insurgent Pick-Up and Insurgent Pick-Up Custom
 * Windsor and Windsor Drop
 * Cognoscenti and Cognoscenti 55 (and their armored variants)
 * Lurcher
 * Fränken Stange
 * Toro
 * Galaxy Super Yacht (can be activated through the Interaction Menu)
 * Marquis, Kurtz 31 Patrol Boat, Patriot Mil-Spec, and Squaddie
 * Rumpo Custom
 * Tug
 * Faction, Faction Custom and Faction Custom Donk (2 variations)
 * Apocalypse Cerberus, Future Shock Cerberus and Nightmare Cerberus
 * Veto Modern and Veto Classic (3 variations)

Trivia

 * In GTA V, if the player adds a custom horn, the mechanic might say "This ain't no La Cucaracha, but it will do." Oddly, even he will say this even if the player installs the La Cucaracha horn. This is likely a game oversight.
 * In GTA V, the "Musical Horn 1" is the Dixie horn, made famous by its use in the show "Dukes of Hazzard". This horn plays the first 12 notes of "I Wish I Were In Dixie Land" and can be applied to the Dukes vehicle (and variants), which is based upon the type of vehicle featured in the series.
 * In GTA San Andreas, pressing the horn button when the door of a mod garage opens after finishing modding a vehicle in a mod garage will cause the in-game radio station to change.
 * In GTA Online, the horn on the players' personal vehicles may change its note every time the player logs into the game.
 * In GTA V and GTA Online, the command to sound a horn on some vehicles is by default the same as activating a special action. For example, police and emergency vehicles are set to activate lights and sirens, while some vehicles such as the Toreador are set to fire their booster rockets. A handful of vehicles, such as the Oppressor Mk II, are given no horns at all.