Not to mention that the third out of four levels crashed everybody's game. Also, a note about "missing AI:" for one, to clarify, this meant that your one opponent literally does not move. There is no race. Second, they made a patch that enabled AI... but it moves, quite literally, at about 1 MPH, and you still can't actually lose; even if it gets to the finish before you, it won't cross the finish line.
In Fuel, you're normally only permitted to race specific vehicles during career races and challenges (sometimes, you're given the choice of just one vehicle). However, by quickly pressing the "show map" button just after the countdown finishes before a race or challenge, you can switch to the vehicle select screen from the map screen, allowing you to choose any vehicle you wish for any race or challenge.
Several if not all of the Mario Kart games (and possibly other racing games) have glitches that allow you to finish a race within seconds. For instance, in Mario Kart Wii, this includes courses like Mushroom Gorge, Wario's Gold Mine, and Grumble Volcano. In Wii, this has sparked a Flame War between pros and non-pros over whether or not using said exploit online is legit.
In Mario Kart 7, a glitch popped up using the respawn feature on Maka Wuhu that allowed a racer to get at least thirty seconds ahead of anyone who didn't use it. It was fixed in a later patch, but some people still try to use it and just look stupid. This is because in order to activate the glitch, after hitting the second section you must drive off the cliff at the right angle, which causes you to respawn at the beginning of the third section.
And there's also the famous glitch from Mario Kart 64's Rainbow Road where if you drive off the wall at the correct section, you'll fall halfway across the course.
In Mario Kart 64, if you rapidly hop to climb uphill near the last turn of a lap in Choco Mountain, your racer will stop in place and tumble there, hovering slightly above the ground and stay there for about 45 seconds, until Lakitu fishes you out of that spot.
In Initial D Arcade Stage 4 version 1.2, hitting walls or turning a corner at too high of a speed would cause your car to lose some of its acceleration. If you quickly release the gas, tap the brake, then step back on the gas, this would negate some of the penalty in what came to be called a "penalty cancel."
Quickly changing from Demolition to any other game mode sometimes left the game with the Demolition mode physics, which meant any other car being propelled hundreds of meters away upon collision, trucks giving way as if they were traffic cones, and almost no damage from any impact for the player.
NPCs spawning on rooftops, only to fall to their death seconds later.
Cars that explode randomly when "destroyed", when a flaming engine is required and usually involves a delay.
Police Cars spawning on top of you. Literally.
Invisible walls blocking passage that can be bypassed, leading to the "fall through the world" sort of glitch. (There's a floor down there, though the landing will kill you if you have anything less than a full HP bar.)
Odd things happening during replays, where events play out incorrectly, sometimes leaving Tanner dead for half of it.
Being slammed into a building by a crash and being shoved up onto the roof.
There was also a median on one map where, if you hit it at a high enough speed, your car would go flying in a straight vertical. Made for a hilarious video.
Driver 2 had a load of these as well, including "fall into the void" polygon glitches.
Driver: San Francisco was prone to a few bugs as well. One mission involves helping a criminal track down a target. The target? Tanner himself, requiring to control his Challenger from an R/C perspective of the Hummer that's "chasing" the target. Should you turn the car you're controlling around and start driving toward the H3 that's supposed to chase him, the chasing car's AI will freak out, causing either of the two cars to fly around like crazy.
The tractor-trailer truck is prone to bugged physics when being viewed in a replay, leading to Fus Roh TRUCK.
Need for Speed: Underground 2's AI cars are vulnerable to PIT maneuvers - even when you're facing the fastest cars, PIT them at the beginning of the race and you have a big head start. In the sequels, AI cars can no longer be pushed.
Note that this isn't even technically a bug; this is game physics actually working.
The police chases in Need for Speed: Most Wanted 2005 have great replay value, thanks to the game's ludicrously epic physics system and police AI. The two sometimes combine in strange ways:
The police helicopter, while coded to swoop down and hit your car, sometimes does nothing except follow you. Other times, it flies in front of you, bumping traffic and police vehicles into the air, or smashing into pursuit breakers (destructible world objects and structures that smash police cars), destroying itself. Otherwise the helicopter is absolutely invulnerable to EVERYTHING, and when it's not hitting your car with an insane amount of force it can be hurling massive, normally immovable trailer trucks across the lengths of the highway at seemingly random times. There are YouTube videos of the 'copter throwing police SUVs or log trucks (logs flying everywhere) in front of the player's car (some of them ending in victories for the police). As if that is not enough, the helicopter will sometimes take part in roadblocks, sitting calmly alongside other police cars. Unlike ramming normal police cars - even the heaviest SUVs - the helicopter will not budge an inch, potentially taking you down from 300km/h to nothing.
While on the subject of weird roadblocks, normal traffic cars (taxis, pizza vans, news vans etc.) sometimes line up with normal police cars, awaiting you to ram into them.
An exploitable design flaw with Spiked Roadblocks is that 999 times out of 1000, or perhaps 1000 times out of 1000, the spikes will either be in the center lane or on the left of the vehicles. Often if you were on the far right you could ram the rightside cop car into submission (unless it was an SUV) or just avoid it altogether.
That said, there's another roadblock glitch, potentially the most malicious one in the whole game. Spikes usually replace a couple of cars in the roadblock, so there's a noticeable gap for you to avoid. However, sometimes cars are put behind the spikes, leaving no visible gap. And when you notice what's in front of them... it's usually too late.
If you hit the curb of a sidewalk and the right speed in just the right way, you'll launch just high enough to do a full barrel roll, land back on your wheels, and still have enough momentum to be doing 80 MINIMUM. The physics engine is horrible, but again, airborne police cars doing what can only be described as a "ridiculously awesome pirouette".
Another glitch involving the police copter is to drive in circles, making the copter do the same. Eventually the AI gets confused and will continually spin in circles.
When your heat level is high, all police cars, including patrol cars, will correspond to that heat level. At heat one, it's the normal Ford Victorias. At heat five... Chevrolet Corvette supercars drive around the streets looking for misdemeanors even when they have only received a complaint about a speeding vehicle (without knowing it is you). This was fixed in Undercover.
Like many other games, both Most Wanted and it's sequel, Carbon, feature glitches that allow players to explore every inch of the game world, driving on thin air.
The AI in Most Wanted 2005 is also notoriously bad. One particular goal for 100% completion is getting into a thirty minute pursuit and escaping. At early stages of the game (when you can't get above heat level 2, and therefore don't have to worry about anything more powerful than a Ford Victoria), it's possible and recommended that you get into a police chase, drive to the bus stop, and drive on top of one of the buses (much, much easier than it sounds). Although there is very clearly a path to your location, the police will instead smash into the bus you're on without effect, and those cops that are smart enough to try and follow the path simply cannot navigate it. This doesn't work at higher heat levels because the Dodge sports cars and Corvettes used by the state and federal police don't need to navigate the path: they have enough speed to launch directly at you and smash you off of the bus. This bug even got to early versions of World, until it was fixed by placing a barrier at the start of the ramp that let you stay over the bus.
Need for Speed World had Team Escape as one of its modes. In it, up to 4 players (2 in the hardest and shortest ones) had to team up and avoid cops in a track that is completely preset (where the cops spawn, as well as roadblocks and spike strips). However, if you are fast enough, cops (ambushing Rhinos in particular) would fail to spawn, making runs a lot easier.
Need for Speed: Porsche Unleashed had a mechanic in career mode where you could buy used cars, or sell ones you owned after racing them (when they had become collector's items). The game described this like it was a risky proposition, so you should be choosy about the ones you pick, but repairing and selling used cars always turned a profit so you essentially had unlimited money once you could afford even one car.
Thanks to oddities in F-Zero X's physics, world-record runs look like this. And this.
This also works in Wipeout, Wipeout 2097/XL and Wipeout 64 since only the track was solid, the scenery wasn't. You weren't supposed to be able to leave the track without being forced to respawn. Well... let's just say it wasn't balanced for Phantom Class racing with turbo boost and any decently fast ship. Quite a few tracks can be massively cut this way. The sequel, Wipeout 3 and especially 3 SE fixed this. Everything is now solid. This causes problems on some tracks where you just plow into the ceiling if you go at any speed.
Fatal Racing required you to win a championship to unlock the next set of tracks. It would accept any championship, regardless of your game settings. Including 2 player mode with no AI cars. Quit out of every race on the starting line and about 30 seconds later you get your tracks.
There are several in the cult classic racing game Stunts (4DSportsDriving) from '90. The most famous one is the power gear, which occurs in several different variants for several different cars. Generally, if you hit a bump or stunt while in fifth gear (some cars have a minimum required speed) the car accelerates to either the cars own top speed or the games ultimate top speed of 245 Mph. The car would stay at this top speed as long as you kept your (figurative) foot down and didn't turn too tightly, even while racing over the grass that usually slows cars down, and while sliding along the fence that guarded the outer perimeter of the playing field. There even is an anti-version of this bug, where the car slows down when the requirements are met.
Another fun bug, occurring under less clear circumstances, is the magic carpet, where the car suddenly jumps up off the track.
It's also possible to drive straight through solid objects. Your chances of pulling that one off depend on your speed and the length of your car.
This game has had a small following ever since the mid-'90s, so websites appeared with downloadable tracks and whole competitions created specifically to allow for the use of these bugs in finding creative shortcuts.
In the same genre as Stunts, Trackmania has fewer bugs and they are usually bad bugs (landing from a dirt jump or on all four wheels at the same time, and randomly smashing into an invisible wall) but the track editor has a number of very, very good bugs. Track pieces in Trackmania have connectors, preventing you from combining arbitrary track pieces that wouldn't fit together. However, if you think you know better, you can use a few simple motions to bug the editor and remove the connectors.
For those who are curious: find any other track piece that can be dragged with the mouse to lay down a line of them, like a regular road. First place an instance of this piece somewhere safe. Then use this piece to drag a line of 2 squares in length starting at a point diagonally to the side of the piece you want to bug and stretching away from it (for instance, if your piece is facing north, you'd make a line starting in the square northeast or northwest of it and going north). But do not release the mouse button to lay down the road - instead, press and hold Ctrl and then press a number key corresponding to any track piece in the menu that cannot be dragged in this fashion (eg. a corner). Now you can release Ctrl and the mouse button. You'll see that the blue selection path remains and no actual track has appeared. Great! Now find a curve or any other piece that occupies multiple squares and attach it to the piece you want to bug so that it completely overlaps the blue selection path. Then press Ctrl and click on the single piece you placed somewhere safe. It will update the blue selection path, filling it in with pieces and destroying the large piece you just placed due to overlap. The connector to which said piece was attached is now gone and you can build anything there. Destroy the now-redundant road and have fun.
There is another easy editor bug to remove track connectors off dirt roads in the stadium environment. Make a dirt hill. Put any uphill dirt road against this hill. Connect your desired dirt road piece at the bottom. Use the height tool to destroy the hill. This will obviously also eliminate the uphill dirt road piece, but the road piece you added at the bottom will not get its connector back. Enjoy building anything there.
The shareware version of Wacky Wheels let you use characters from the registered version by viewing the help screen (which would depict a race from the vantage point of a random character) and load a game. That character would have been loaded into memory and replace the character in the saved game. You could also drive on one registered version track by doing the same trick with the Order Info screen (which depicts a race on Silver Wheels 2), but the game would crash after the race was over.
In Top Gear for the SNES, it is possible to get both 1st and 2nd place or any two sequencial places in a race. This is done by running into the pole at the finish line before crossing over. You will get the points for both places, making it much easier to rank 1st place for the country.
There are several places in Cruisin' World for the N64 where you can deliberately drive off the side of the road into a solid wall at full speed, and rather than crash, you will appear a goodly distance further down the course, usually flying through the air performing a stunt.
In Gran Turismo 5, there is a glitch that allows you to clone cars. Just borrow the car of your friend, delete game data, start the game up again, refuse to install patches, change to a car that you own, start the game again, install the patches, and own the car you borrowed. Oh, and this is hardware-related so NO amount of patches will fix it.
Kirby Air Ride: During one of the City Trial challenges, you have to fly your machine as far as possible until you hit the ground. Normally, when people want to do this they'd pick the Wing Star, or, if at all possible, the Dragoon. However, if you charge up your Bulk Star to full capacity, drive of the ramp, and rhythmically press the brake button, you will fly indefinitely until you mess up or reach the maximum possible distance. The legendary machine built for flying can't even make a quarter that distance!
In the original Crazy Taxi, and all it's remakes, if you 'crazy drift' into a wall and hit it at a parallel angle, you will quickly rack up tip combos, and make massive amounts of cash. Doing this is a necessity for getting over $2,000 per trip.
In Wangan Midnight Maximum Tune, Story Mode "unbeatable" opponents (marked by a chevron but no "R" icon to indicate that they do not need to be beaten to win the stage) and opponents about to break down or back out of the race will gain a speed boost, with said speed boost being higher than your car's top speed if you are at full tune. If you manage to get in front of the car, it is possible for said car to push yours to extremely high speeds, as high as 440 km/h! (For reference, the highest speed attainable under normal conditions is 351 km/h.)