Yes, giant robots from outer space that turn into cars exist in the Television Crossover Universe, because the TVCU is a reality pieced together by crossovers.
Note that the Transformers's battles happen mostly in secluded locations, and so though there are a number of people who know about them, such as the government and certain civilians, most people, even if they've heard of them or seen them, don't believe them to be real.
1977--G.I. JOE VS. THE TRANSFORMERS: BLACK HORIZON--Cobra imprisons Joe Colton.
1984--TRANSFORMERS # 3--I had previously stated elsewhere that Spider-Man had probably never returned from the Secret Wars, but then James pointed out that an older Spidey was still operating in more modern times, and here is more proof that he returned with the suit that would be Venom. One of the Transformers would later appear in Secret Wars II, but I do not consider major Marvel crossovers as TVCU canon. However, I do believe that Secret Wars II may be yet another part of the Crisis. Nick Fury also appeared in the original Marvel Transformers comic series.
October 1985--G.I. JOE--"Twenty Questions"--The first appearance of the character Hector Ramirez, a TV journalist lacking in integrity. Ramirez also appears in THE TRANSFORMERS, JEM AND THE HOLOGRAMS, INHUMANOIDS, and TRANSFORMERS 2010, as well as the Devil's Due G.I. Joe comic, where he is killed by Cobra in # 40 for bringing sensitive information to Joe Colton. It should be noted that Ramirez is meant to be Geraldo Rivera, and I agree, which of course means that Geraldo was killed in the TVCU in 2005!!! I don't buy it though, and think he must have survived. Geraldo has also appeared as the fictional TVCU Geraldo in SAIL TO THE CENTURY, ALL ABOUT STEVE, THE MIRACLE OF SPANISH HARLEM, THIRTYSOMETHING, HARD TO KILL, EMPTY NEST, NURSES, THE CRITIC, GRUMPIER OLD MEN, MEET WALLY SPARKS, CONTACT, COP LAND, MEN BEHAVING BADLY, NASH BRIDGES, PRIMARY COLORS, SEINFELD, HEARTLAND, THE SOPRANOS, and MY NAME IS EARL.
November 1985--TRANSFORMERS--"Prime Target"--A Decepticon shoots down a member of the October Guard, the Soviet counterpart to G.I. Joe.
December 1985--G.I. JOE--"Cold Slither"--Cobra creates a rock song that goes to the top of the charts and has a subliminal track to hypnotize people.
December 1985--TRANSFORMERS--"Auto-Bop"--The Decepticons use the song "Cold Slither" to hypnotize humans at a disco.
1986--G.I. JOE AND THE TRANSFORMERS--Cobra forms an alliance with the Decepticons, but turns out, the Decepticons were being deceptive. Really, Cobra Commander? Didn't see that coming? It's even in their name. So then Cobra turns to G.I. Joe and the Autobots to stop the Decepticons from destroying Earth.
Between 1986 and 2005--TRANSFORMERS--"The Binaltech Story"--This storyline involves an investigation of a government agent named “D.R. Faireborn”. That's G.I. Joe's Flint, father of Marissa Faireborn, a regular character in Transformers. Incidentally, Flint's father was one of the original government guys to work with the Autobots. There's also an appearance of the "Concurrence", a secret evil group founded by Count von Rani aka Iron Claw, enemy of Sergeant Savage and G.I. Joe Extreme.
1987--SPACEBALLS--It's hard to date this, but I do know at some point the Spaceballs visit 1980s Earth, so... Anyways, their ship is actually a Transformer, though apparently one lacking sentience.
1989—“Plan Six from Outer Space”
Splinter is kidnaped and replaced by a robotic transforming alien. The robot self-identifies as a “Pretendicon.” A version of the Transformers do exist in the TVCU, so it seems likely that this “Pretendicon” was a Decepticon. What a Decepticon would have to gain from impersonating Splinter is yet to be determined.
1990--INCOMPLETE DEATH'S HEAD--The Doctor (Who?) tells Death's Head that he was responsible for sending Death's Head to the universe of the Transformers, meaning the TVCU.
November 2003--FAMILY GUY--"When You Wish Upon a Weinstein"--When the nuns are leaving the church and boarding the bus, the Batman villain Penguin is outside jumping for joy going “Excellent, excellent!” and delivers his signature laugh. The gag is a reference to the slang term “penguins” which is often used to describe nuns due to their traditional black and white uniforms, and the fact that the Penguin used trained penguins in his crimes. Furthermore, in the old Batman series, Penguin’s henchmen wore black and white costumes, the same colors as the nuns’ habits. A short cutscene, which parodies the rumored dangers of laser eye surgery, Star Wars character Luke Skywalker, who wields a lightsaber to execute the surgery on the encouragement of Obi-Wan Kenobi. Optimus Prime, leader of the Autobots on Transformers shows up to the Quahog synagogue for the Sabbath service. Also appearing isLenny Kravitz who being half-Jewish, is shown with only half of his body present.
2004--GODZILLA--A MASER tank is a vehicle created in the Japanese Godzilla movie series. This would make Signal Flare's Terrorcon counterpart Cruellock, who is patterned on the 1998 American-movie version of Godzilla. MASER tanks never really worked all that well against whatever giant monster was stomping around each week. Development sketches from Aaron Archer reveal that part of the inspiration for Signal Flare's vehicle mode was the distinctively-shaped Cobra H.I.S.S. tank from the G.I. Joe toy line. I don't consider the American version of Godzilla in the TVCU, though, or the TVCU2 for that matter, but it could be it happened in the Mirror Universe? That maser tank gets a lot of mileage. It even appears in multiple Godzilla continuities (Showa, Heisie, X Mechagodzilla). They also show up in Ultraman, Project A-Ko 2 and Fight! Iczer 1. and Sgt frog apparently It's also totally Canon with soul caliber
November 2005--FAMILY GUY--"The Courtship of Stewie's Father"--Peter, dressed as Indiana Jones and Stewie, dressed as Short Round are chased by a turban-wearing guard named Ahmed through a mineshaft, parodying Indiana Jones and the Temple of Doom. Upon luring the guard away, Michael Eisner tries to rip out Peter’s heart parodying Mola Ram from Temple of Doom, but falls down a cliff by the Jungle Cruise and is ripped apart by crocodiles. During a cut-away scene Peter is conducting the Tusken Raider Choir. The Tusken Raiders run away, when Obi-Wan Kenobi enters to say that the Sand People frighten easily but they'll be back and in greater numbers. This specific line is a scene from Star Wars. In the scene where Peter rescues Stewie from “It’s a Tiny World” and Ahmed the guard goes after them, Peter’s line to distract him, “Hey, look over there! There’s a woman learning!” was cut on the FOX version, presumably because it would cause offense to Muslims. The Adult Swim and DVD versions have the line intact. When Peter’s socially awkward and “burden of the state” supervisor, Opie, is promoted, the evil Decepticon Soundwave (from The Transformers) inherits his job. Soundwave has a wife he met in a Christian chat room, and carries a picture of his family that transforms into a cassette tape. Compared to “When You Wish Upon a Weinstein”, it had previously established Optimus Prime, leader of the opposing Autobots, as Jewish. Peter realizes that Stewie has run off whilst they are shopping in a Disney shop. He spots the Crows from the Disney film Dumbo sitting in the shop. He asks them if they have seen Stewie. The response: "Well I done seen about everything but I sure no seen your boy no how" in an African dialect. Peter's response is the same: "Ahh, that's good old fashioned family racism."
2006--G.I. JOE VS. THE TRANSFORMERS: THE ART OF WAR--A new foe seems to have all the combined memories of Serpentor and Megatron.
2007--TRANSFORMERS: THE HEADMASTERS--The Autobots encounter the BATTLE BEASTS, who get their own spin-off. Later, the Battle Beasts will again meet the Autobots in a Transformers manga.
2007--G.I. JOE VS. THE TRANSFORMERS: BLACK HORIZON--Colton is rescued from his prison in Cobra-La, which must really be Shangra-La from LOST HORIZON.
October 31, 2007--BILL & TED'S EXCELLENT HALLOWEEN ADVENTURE--James says: Apparently Bill and Ted meet Dr. Doom, Dr. Evil, Jack Sparrow, the Transformers, and who knows what else. http://www.billandted.org/halloween.htm
September 2009--TRANSFORMERS # 284--Guest starring the G.I. Joe Action Force, a Predator hunts Starscream.
2009--COMMUNITY--"Comparative Religion"--Just when I'd thought I'd found all the surreal Community crossovers... Pierce's weird cult-like religion uses Energon cubes. These are cubes of pure energy that the Decepticons use to fuel their ship, and the primary source of fuel on Cybertron.
2010--COMMUNITY--"The Psychology of Letting Go"--Once more Pierce mentions Energon Cubes in regards to his religious beliefs.
2010--TRANSFORMERS 2010--"The Killing Jar"--It's revealed that Marissa Faireborn is the daughter of G.I. Joe's Flint. Flint's father was the military leader that first worked with the Autobots when they first came to Earth in the first Transformers series. Lady Jaye is Marissa's mother.
2010--TRANSFORMERS 2010--"Only Human"--Tired of the Autobots interfering in his operations, a crimelord seeks the aid of Cobra Commander. Yes, there are Transformers in the TVCU.
3011--FUTURAMA--"Reincarnation"--A monkey Transformer is named Gigatron (which is Japanese for Megatron).
EARTH-616-2--Yeah, or something. In this reality, G.I. Joe is a team in the late 1930s, which is when the war between Autobots and Decepticons begins. And Cobra is an independent terrorist group during this era. This is all seen in TRANSFORMERS/G.I. JOE from Dreamwave Productions. The sequel, sen in the same reality, is TRANSFORMERS/G.I. JOE: DIVIDED FRONT, which is set in the mid 1980s.
- February 2006--DRAWN TOGETHER--"The Lemon-AIDS Walk"--The cast plays badminton against another team of celebrities, which are THOMAS THE TANK ENGINE, the creature from WHERE THE WILD THINGS ARE, STIMPY (of REN & STIMPY), THE HAMBURGER HELPER HELPING HAND, an old political cartoon, and a TRANSFORMER. I place the TRANSFORMERS in the TVCU, but it could be the events of the 80s cartoon also happened in the Looniverse.
- October 2006--DRAWN TOGETHER--"Wooldoor Sockbat's Giggle-Wiggle Funny Tickle Non-Traditional Progressive Multicultural Roundtable!"--Foxxy and Ling-Ling watch a porno with TRANSFORMERS.
ROBOTECH UNIVERSE--This is a future that diverges from the main TVCU timeline with the arrival of the Transformers (or awakening rather) and leads to a very alternate present day and future. Salvatore Cucinotta adds: The Veritech/Valkyrie fighters were actually re-purposed by Takara to become the transformer Jetfire. There's other similarities beyond designs and a basic starting point (crashed alien ship with technology for transforming machines), and it sort of goes to support a thesis I have that "In space: No one likes the Transformers" Millenia-long periods of War tend to annoy other races when they get drawn into it. But on that note, Transformers G-1 designer, Kunio Okawara, used the same basic design for the mechanical life forms from "King of Braves: GaoGaiGar", which shares the 1999-alien-crash-brining-advanced-technology-and-deadly-enemies theme with Macross. It's because of that, I tend to dovetail them for simplicity's sake. I like merging events for fleshing them out. But that one connection does exist. Though GaoGaiGar has a lot of super-tech to it that stretches the lower-powered nature of most crossover universe and would not be out of place in the 22nd century/in the time of space exploration. Though it would be in the earlier part of it (IE: Just-Pre-Warp), where humanity is limited to the solar system (just touching Jupiter) works a bit better for all of them future-placement-wise. I tend to place both in alterante universes for Kaiju Timeline purposes. Then again, Kaiju Timeline-wise, I mix Gundam's One Year War with the Maquis Rebellion in Star Trek. Making the Maquis "Zeon".
TVCU2--This is the divergent timeline of remakes. This is where the current IDW series is set, because they love to buy our favorite stories just to say they no longer exist. There have been a few crossovers. In Infestation, zombies from the universe of ZOMBIES VS. ROBOTS are somehow sent through time and space to the 23rd century of the TVCU (STAR TREK) and the present day TVCU2 (G.I. JOE, TRANSFORMERS, and GHOSTBUSTERS.) The Universe of CVO is also involved. Then, in Infestation 2, LOVECRAFTian horrors attack in the present day TVCU2 (G.I. JOE, TRANSFORMERS) and present day TVCU (TEENAGE MUTANT NINJA TURTLES, 30 DAYS OF NIGHT, DANGER GIRL).
WHONIVERSE--Caeric ArcLight says: Made a DVD run at some of the local pawn shops and was reminded of a neat 'crossover.' In the first TRANSFORMERS movie, Travis Van Winkle played an egotistical jerk named Trent. In the FRIDAY THE 13TH remake/reboot/sequel, Travis Van Winkle played an egotistical jerk named Trent. Rob adds: Whoah. And in 2007's Transformers he was in high school, and in 2009's Friday, he was in college. What a good catch. Of course, this is difficult for my TVCU theories, since I place the Friday film as a sequel, and I can't have a world where entire cities are devastated by robots in the TVCU. And even though the TVCU2 is a world of remakes and has lots of cities being devastated in the past decade, which would allow a version of the Friday film that views it as a remake to fit there along with the Transformer films, I've already placed the IDW version in the TVCU2. However, certain connections to the Whoniverse with the film have been made, with some appearances of the film versions of the Transformers existing in the same NFL promo world as other Whoniverse denizens. The Whoniverse is a great place where alien invasions happen all the time, then the world just forgets about them.