A favourite assassination method of mobsters and spies alike is to hook up a bomb to the ignition switch of a car, so that it will lie dormant until some poor soul starts it.
While the intended target is, naturally, the car's owner, this trope is the number one killer of chauffeurs and valets — which occasionally raises the Fridge Logic of why you would put an ignition-triggered explosive in a chauffeured car in the first place — and has claimed its fair share of helpful Dead Sidekicks and Disposable Women as well.
There is an interesting case of The Law of Conservation of Detail attached to this trope. In normal circumstances, little to no screentime is devoted to a character walking to their car or starting it. Hence, whenever this does happen — especially if you see a close-up of the key — the more Genre Savvy viewer probably has a distinctly uneasy feeling in his stomach. Wait for it... three... two... one... ignition! Another dead giveaway is if the car is a gift from someone the recipient really shouldn't trust.
Variations include remote-detonation and bombs hooked up to other parts of the car, but the idea is to kill the occupant. Cars turned intosuicide bombs don't count.
A subtrope of Vehicular Sabotage. See Every Car Is a Pinto for cars blowing up that have no reason to.
Unrelated to steam engines and Stirling engines, which really do work by "external combustion".
One of the manga adaptations of Mobile Suit Gundam, ''Gundam: The Origin", covers a lot of backstory from prior to the start of the anime. One scene has loyalists of spacenoid leader Zeon Zum Deikun use a car bomb against the sons of his successor Degwin Sodo Zabi, who many suspected of having assassinated Zeon to take his job.
Golgo 13. A criminal gang attacks a hijacker who's parachuted into the Amazon with his three million ransom. Actually they've been Lured Into a Trap, as the hijacker is Duke Togo who has a contract on them. As Duke masscares the attackers with machine guns and rocket launchers he's prestashed in the area, their leader decides Screw This, I'm Outta Here! and runs for the vehicles. One of his mooks starts a vehicle a moment before he does and blows up. The leader looks at his own ignition key, throws it away and decides to go on foot. He doesn't get far.
In the BatmanKnightfall saga, a villain has stolen the Batmobile. Batman gets in the car, starts it, and kaboom! Cut to Robin screaming, when Batman walks by and says he got out just in time, realizing it was booby-trapped, "because that's what I would have done."
The Punisher once ran into villains who took to modifying taxis with booby-traps that would horribly kill the driver. When he realized this, he switched cars with the bad guys pursuing him, who forgot whose car the remote activated...
Yuri's uncle in Lord of War, after Yuri gifts his car to him.
Subverted with a side order of Dangerously Genre Savvy in the film version of The Sum of All Fears. Dressler has his bodyguard start the car first, as he's savvy enough to know people like him get offed this way. After a tense moment, the car starts just fine. When Dressler (who was established early in the film to be a chain smoker) pushes in the car's cigarette lighter, it explodes as soon as the lighter pops back up. The bodyguard who started the car survives.
Parodied in Mafia (the Jay Mohr comedy), where Mohr's character is in the car when this happens. He survives, but loses most of his skin in the accident (leading to a major Squick moment when he eats a tangerine, leading to a multiple Vomit Indiscretion Shot). By the time he meets up with his wife again, he only has a small bandage on his cheek. When he is asked what happened, he replies, "Car exploded."
Famously done in the opening scene of Casino. Sam is narrating to himself as he walks out of a restaurant into his car, and it explodes when he turns the key. Subverted, however, as we see later on that he survived.
Sam: When you love someone you've got to trust them, there's no other way. You've got to give them the key to everything that's yours. Otherwise, what's the point? And for a while, I thought that was the kind of love I had.
In The Dark Knight, a judge is shown out to her car by secret service types with sealed instructions as to her destination. When she opens the envelope, the note contains only a single word: "UP". BOOM.
As with the book, so with the film: in The Pelican Brief, attempting to kill the protagonist.
A mob boss in The Gang That Couldn't Shoot Straight is terrified of being killed by a car bomb and always has one of his underlings start his car for him. At the end of the film, he is killed by a bomb that is triggered when the driver's door slams after the engine has been started.
In Scarface (1983), Tony is supposed to help a hitman kill a government official with the remote-detonated variant. He refuses to do sowhen he sees the official's kids get in the target car.
Wise Guys has testing a car for this as Danny De Vito's chore, as the low man in the Family. Wincing, he turns the engine over, and doesn't blow up. He makes it back to the other happy laughing mobsters, including his boss, and they chat. THEN it blows up.
The Transporter. In the second movie the villains have attached a remote-controlled bomb to the bottom of Frank's car, which he sees reflected in a puddle of water. As the villains are pointing guns at him he has to get in anyway, and detaches it by launching the car into the air so the magnetically-attached bomb is knocked off by a crane hook. It would have been a lot simpler for the villains to have just shot him, or for Frank to have parked the car and ran away as soon as he was out of sight, but well...
It isn't the first time someone's tried to use a car bomb on him — the first movie has The Dragon attempting to get rid of him with a bomb in a suitcase, resulting in his car going kaboom.
In the original version of The Mechanic, McKenna gets into his car at the end of the film, realising too late it was rigged to explode by Bishop, who knew that McKenna would eventually kill him.
Michael Collins features one of the assassinations of British agents as being accomplished via this. The use of such a method in the time period (as well as the Northern Irish agents featured) is entirely fictitious, and an obvious reference to The Troubles.
Alex Murphy becomes the eponymous character in RoboCop (2014) when this is done to him.
Law Abiding Citizen. The Well-Intentioned Extremist put remote-controlled bombs inside the gas tanks, where a prior search didn't find them. The protagonist is Forced to Watch as the woman he mentored struggles to escape from a vehicle with sabotaged locks as the other cars explode one by one, before her car also blows up.
In Ordinary Decent Criminal, a judge is intimidated by planting a bomb in his daughter's car, triggered by the remote unlocker. The fact that it blew up right in front of the judge, and only injured his son-in-law instead of killing his daughter or himself, makes it a bit of a Xanatos Roulette as far as intimidation tactics go.
Stephen King short story Dolan's Cadillac involves a guy whose wife was killed with a car bomb (she had information on a local mob boss). The rest of the story details how he gets his revenge.
Happens in the Stephanie Plum book One for the Money, with the car she appropriated from Morelli (in this book, he's the skip she's chasing). Another of Vinnie's bounty hunters is the ill-fated person who starts the car.
White Night has Murphy's car wired with a pipe bomb by one of the villains, who doesn't want her and Harry looking into a series of serial killings. Fortunately, Harry was just a little bit pissed off from a meeting the scene before, so he lets off a hex to blow off some steam... which just happens to activate the car bomb's detonator while he and Murphy are across the street.
The non-fiction Prince of the City. Corrupt NYPD detective Robert Leuci, who was testifying against his former colleagues, would have his police bodyguards check his car for explosives every day. Showing typical cop humor, the bodyguards would then stand on the street with their fingers in their ears while he turned the ignition.
British agent Quiller was the target of one of these in Tunisia. Fortunately, the bombers didn't have the chance to wire the bomb to the ignition, so they set it to go off when the car experienced a sharp vibration, such as the door closing. And then a heavy bus rumbled by and triggered it while Quiller was still halfway across the street. In Adam Hall's typical narrative style, it's stated:
So at 19.15 I checked out of the Hotel Africa and went across to where the Chrysler was parked and they said later at the hospital that the glass had been the worst trouble because some very small fragments had got stuck in my face....
In the first Quiller novel, the carbomb is placed in the suspension, rigged to go off when it falls and hits the ground as the car starts moving. As Quiller needs to fake his death to escape surveillance, he starts the car's engine and leaves the bomb on the hood, hoping the vibrations will cause it to slide down the hood, fall off and detonate. After a while nothing happens, and Quiller thinks the bomb has got stuck and he'd better go back and dislodge it, when the garage blows up in his face.
Happens again by accident in Quiller's Run. Quiller has been boxed in by an extensive surveillance team. As night falls, another agent of similar build plans to drive away in his car in the hope of leading off the enemy so Quiller can escape. It works better than expected because a bomb had been placed in his car. The surveillance team quickly vanish before the police show up, thinking Quiller has been killed.
Happened to one of Dirk Pitt's many vintage automobiles. He wasn't in it, and he had it restored at the end of the book.
In the first book of the Left Behind series (and its film adaptation), Alan Tompkins was killed by a bomb planted inside his car.
The second high-profile assassination in the first chapter of Never Send Flowers is a politician whose car was rigged with a bomb. The thing wasn't set to explode immediately, it took eight startings of the vehicle before the inevitable.
Artemis Fowl manages to calmly deduce Holly's presence from the fact that Butler, the world's best bodyguard, didn't do his usual bomb check, and just about the only thing that would interfere with his reflexes is fairy mesmer.
Live Action TV
Criminal Minds deals with the problem mentioned above in an interesting fashion in the Season 3 finale. We see all the team getting into their respective cars, in a way that practically screams "car bomb". But because they're official FBI vehicles, they all are driving the same car. The episode ends with one of them blowing up, but without showing which one. It was the one that Hotch and his old friend who happens to look just like his (ex?)wife and had been introduced in the same episode. He lives, but she dies at the hospital.
In The X-Files episode "Fire," Mulder and Scully get into their car to find a strange cassette tape on the dashboard. They pop it in, and a voice informs them that by doing so they have armed a bomb hooked up to the car, and opening the door will trigger the explosion. Someone then opens the door from the outside, and Scully jumps—turns out the voice on the tape was just Mulder's New Old Flame, trying to mess with their heads.
Burn Notice has Sam and Fiona do this accidentally - they were meant to hook up a small explosive charge to the electrical system to enable them to remotely disable the car, but it turns out Fiona attached it to the petrol tank... fortunately the target uses his remote starter, blowing the car up before getting anywhere near it.
A later example has someone try to ambush Michael with one, only to discover Mike had removed the detonator when the guy went to the toilet.
A group of mercenaries take a more direct approach in another episode, the crooks that the gang was following get into their car only for it to be hit by a missile fired from the other side of the canal.
Several times Michael has Exploited this trope for Gaslighting purposes by simply disabling the ignition on the car of someone who's already paranoid (either thanks to Mike or because they're in a dangerous line of work to begin with).
Monk's wife's Death by Origin Story is a textbook case. More show up over the course of the series, sometimes hitting their intended target and sometimes not.
A clip of one of these going off is part of the Opening Montage to the "MacGruber" recurring filmed sketch on Saturday Night Live.
Used in Fox News' infamous "Hackers On Steroids" 4chan expose.
In an episode of F/X: The Series, a main character is saved from this by her habit of remote-starting the car with one of Rollie's gadgets: The car explodes in front of her and she's hospitalized.
In "Did You See The Sunrise?" one of these, intended for Magnum, kills recurring character Lt. MacReynolds instead. Magnum is not happy.
Magnum's wife and daughter were killed when a bomb set in their car went off. Later, he finds out that his daughter actually got out moments before, leading him on a quest to find out if she survived and where she is.
Hunter. A journalist writing a story on the mob is apparently blown up in his car. Later his wife is shocked to find him turn up at their home in the middle of the night; when she asks who was in the car he replies: "The unluckiest car thief who never lived."
All My Children did something similar when investigative journalist Edmund Grey was tailing a corrupt politician, shocking his wife and his other loved ones when he walked into his own funeral and revealed that the politician himself must have died in the explosion. Apparently the man didn't trust his own lackeys to do the job right and decided to plant the bomb himself.
Another Hunter episode had the bomber using the "someone else starts the car" to his advantage. He was a police chief who wanted to kill his wife, so he left his car in the driveway so that his wife would have to move his car to get hers out, activating the carbomb that was supposedly left for him.
The Professionals ("The Purging of CI5"). Bodie and Doyle have just escaped a bomb in their phone, and Doyle worries there might be another in the car they've just gotten into. He suggests Bodie wait across the street while he starts the ignition. Bodie just gives him a contemptuous look and says "Oh just stick it in!" (There's no bomb).
Spoofed in the Community episode "Conspiracy Theories and Interior Design", when a car belonging to Annie is rigged to blow to scare her and Jeff off investigating the college's night school and the mysterious Professor Professorson... except the car in question is a small model car on a diorama she's constructed, and the 'explosion' is a handful of small, insignificant sparks.
Jeff: Looks like someone sent us a message... a tiny, thoroughly underwhelming message.
In the Miami Vice pilot, this is what happened to Crockett's first partner.
This occurred once or twice on The Rockford Files. However, the interesting part was not the explosion, but rather Jim's attempt to explain what happened to his insurance agent.
An episode of My Name Is Earl in which Earl was studying for a GED ended up with this trope as a downtrodden teacher was convinced to play a trick on an unruly student but got some wires crossed. The car was supposed to lock the teenager in and play an annoying tune, but the results were a bit more dramatic.
Referenced in the finale of Angel. Izzy and his minions get into their car and there's a closeup of a hand turning the ignition key — but instead of an explosion we get Illyria revealed in the headlights, and after a cutaway the vehicle looks like it's been carbombed.
On General Hospital, Sonny's wife Lily was killed this way, when her father planted a bomb meant to kill Sonny, enraged that he had not stopped carrying on with his ex-girlfriend. The sad irony is, Sonny and Lily had just reconciled and resolved to start over. She was driving the car because Sonny had drunk too much champagne celebrating her pregnancy. The scenes played out very much like in the play description—a joyful Lily walking towards the car, turning to smile back at Sonny, getting into the car, starting the ignition. . .cue the sound of the explosion and a Big "NO!" from the now widowed Sonny.
Tracker This was attempted in "A Made Guy", but Cole used his abilities to hyperspeed and manipulate electronic devices to disable it before it could go off.
Used on a number of occasions by the Leverage team and their opponents.
This is the backstory of Detective Levon Lundy of Houston Knights; the criminals he was investigating decided to get him off their case permanently, but unfortunately his wife took the car out that morning.
Played with in an episode of Castle. We see a character get into a car and die when the car explodes, leading to the usual expectation that someone planted a car bomb. As it turns out, the car was hit by a guided missile.
Rizzoli & Isles: In "Bulit for Speed", the Victim of the Week is a street racer who is killed when his nitrous tank is replaced with propane and detonated with a remote detonator.
Foyle's War: A grenade wired to the steering wheel and rigged to explode when the door is opened is used to kill a former Nazi in "Sunflower". Or so it seems. Actually, the explosion was used to fake his death.
Major Crimes: The Body of the Week in "Year-End Blowout" is a used car dealer killed by a bomb placed in one of his vehicles. A second bomb later turns up in the car of the company's comptroller.
The pilot episode of The Pinkertons gives this trope a 19th century twist: the villains try to sabotage a passenger train by disguising explosives as lumps of coal.
Dick Tracy had this as the way they killed off the Creator's Pet, Moon Maid. The twist is that instead of being under the hood, the bomber, Little Lettel, preferred to place his bombs under the dashboard in the interior of the car.
If you return their brains, Maloof (who is implied to be from a mafia family) and Mikhail of Psychonauts can be found rigging Coach Oleander's to explode. Since he's last seen leaving the camp in a jet, we don't know if it ever worked.
Déjà Vu has a booby-trapped car that will explode if you start the ignition or pop the hood.
In Family Guy, when Lois is wanted by the mob, the valet retrieves their car shortly after a hit is called off. It ends rather poorly for the boy.
When Homer Simpson was the Mayor's bodyguard, and the mob had threatened to kill him, he tries to get Bart to "start daddy's car for him". When Marge protests, he decides to get a cab.
One of Bill Plympthon's early shorts had a vignette titled "The Mafia, the Early Years", which showed a cowboy's horse blowing up after he spurred it.
An episode of American Dad! has Roger plant bombs in the cars of three teachers at Steve's school after they gang up on him. Only the first two bombs actually go off; the third teacher suddenly becomes Made of Explodium and his torso explodes, leaving behind his legs.
Commonly used by terrorists and guerrillas in real life. Although popularly associated with Middle Eastern hot spots, the basic structure of the car bomb was invented in the 1920s.
He survived because a Good Bad Bug in the car's balancing system necessitated a heavy steel plate be installed under the driver's seat to compensate.
The Irish Gang War of Boston in the early 60s escalated when one gang tried to wire a bomb in the car of the wife of the Winter Hill Gang leader.
The Winter Hill gang would later bomb the car of the lawyer of Joe "The Animal" Barboza, who, at that time was a government witness. The man who helped arrange the bombing Frank Salemme, would later become a notorious informant for the FBI.