Types of Exploding Vehicles
Exploding vehicles are rare, but not entirely unheard of occurrences in the Grand Theft Auto franchise. In fact, exploding vehicles were far more common in games that took place in the 3D Universe (Grand Theft Auto: Vice City, Grand Theft Auto: San Andreas, etc.), than newer games set in the HD Universe (Grand Theft Auto IV and Grand Theft Auto V).
In games like GTA San Andreas and GTA Vice City, exploding land vehicles often occur as a result of three possible reasons.
When in free-roam, players can sometimes encounter cars traveling down roads at speeds near terminal velocity. As a result of possibly faulty AI scripting for NPCs, NPC drivers might spawn already set into Panic Mode (when an NPC reacts to a nearby incident, such as a gunshot or murder). If the NPC does not exit their vehicle while in Panic Mode, they will press the acceleration of their vehicle, until they hit top speed. Once the driver is in this state, killing them will become the only means of pacifying them. Essentially, the NPC becomes a Deadly Driver. If the vehicle is speeding long before its encounter with the player, the vehicle will probably be smoking or burning to the point of destruction. These types of vehicles are found in every game set in the 3D Universe. On rare occasions, these vehicles can be seen driving into a wall and exploding on impact.
One of the most common types of Deadly Drivers is Highway cars. While not exactly in Panic Mode, these types of NPCs are scripted to spawn driving at speeds of 60 MPH (miles per hour) and higher. While this scripting was intended to simulate high speed driving on busy highways and freeways, they often (if not always) drive at speeds that allow them to crash into other nearby drivers as well as pedestrians and players. If a player or unlucky NPC driving at normal speeds happen to find themselves driving on a highway, they are more than likely going to be hit by a car bulleting towards them. Once the speeding vehicle has plowed through enough traffic, it will ultimately explode on impact. In San Andreas, these vehicles are commonly found on freeways and highways around San Andreas, especially near Mount Chiliad and Las Venturas. Players will often hear or see vehicle explosions in these areas, if they are not triggered by damaged vehicles in Panic Mode. Sometimes, players can even see vehicles spawn at top speed already and explode upon impact with the first vehicle they hit.
This phenomenon often occurs when an NPC-driven vehicle encounters some sort of conflict in its scripting upon spawning. While the previous type is linked to a chain of events, a bad spawn is essentially a vehicle that explodes the moment it spawns. Bad spawns can also cause a vehicle to spawn turned over (which guarantees the vehicle exploding). On other rare events, planes and cars can spawn clipping into objects and surfaces and explode instantly.
While not unheard of, this phenomenon can still surprise even experienced players. As the name implies, roaming airplanes and helicopters have a tendency to crash into obstructions (tress, buildings, etc.) as a result of them being in the way of the aircraft's fixed flight path. Aircraft can also crash by flying at dangerously low altitudes. On most (if not all) occasions, the aircraft will explode on impact. These are most often spotted in GTA San Andreas.
It is possible the cars explode because of the riots, where NPCs are given the power to be as destructive as they want (only occurs in Los Santos). This includes destroying vehicles. This only occurs at the end of the game, after Officer Tenpenny is pardoned for his crimes. Killing him in the final mission will stop the riots. However, this is exclusive to GTA San Andreas. It may also occur by use of Riot cheat.
Exploding vehicles in games set in the HD Universe follow similar patterns to 3D Universe variations, however, this does not mean they are the same. There are also types of exploding vehicles that only occur in the HD Universe.
A common cause for exploding vehicles in Grand Theft Auto Online is multiple vehicles spawning in the same location at once. When more than one player is adjacent to a unique vehicle spawning location (such as helipads and airfields), the games scripting may attempt to spawn aircraft on the same location over neighboring spawn points. With the relatively delicate nature of aircraft in GTA V, the vehicles may spawn on top or inside of each other and explode instantly. The game's inability to spawn vehicles in available locations is more than likely the result of lag caused by the number of players present in the session.
This player-made variation of the exploding vehicle can be created by installing an ignition explosive or remote detonated explosive in a player's vehicle. While often mistaken as being the result of session lag, these variations are often encountered by attempting to steal a vehicle from a very cautious (or simply paranoid) player. Rather than purchasing the explosives installation, a player can also place a concealed and well placed sticky bomb for unsuspecting victims.
After the Last Team Standing update, players can hear random explosions go off close to them. It is believed this might be caused by either Deadly Drivers, or cars spawning inside each other.