Grand Theft Auto: The Trilogy — Definitive Edition may have shredded some signature tunes from the series’ radio stations, and may, in just about every conceivable way, make the descriptor of “Definitive” sound like a joke, but—at the very least—you can still make an invulnerable, wiggly, and constantly swelling car in GTA III. This glitch, unlike the game’s incredibly ugly rain, weird draw distance, and rounded nuts, cannot be blamed on a rushed remaster. Rather, it’s a holdover from Grand Theft Auto III’s original release.
The glitch, which shows a car slowly increasing in size as the driver wiggles it back and forth, is actually the second part in a three-part glitch which makes cars immune to collision damage, which you can perform through this involved setup.
To begin, you have to find a taxi. Finding a taxi will allow you to enter a taxi mission, which in turn allows you to pick up the passenger you’ll need later. Once you’ve entered the taxi, hold R3 (the button in your right thumbstick), and exit the vehicle while still holding R3. If you get into a vehicle while still holding R3, you can start using any vehicle as a taxi.
Once you begin your taxi mission, pick up a passenger and take them to the car crusher in Harwood. Park your car with the driver’s side door facing the crusher and then exit the vehicle. With a passenger inside, you won’t be allowed to exit through their door, so instead you just teleport out. The car crusher will then attempt to grab the not-taxi, passenger in tow, at which point you should enter the vehicle. Once the game realizes that you’re in the car, the crusher will drop the car and the glitch will be active.
Your car now phases through non-terrain objects, including buildings. It will also slowly increase in size, which can be sped up by quickly wiggling it as you drive. The car will keep growing until you reset it by falling through the world geometry.
There’s a third, much simpler part of this glitch. Once your car becomes a ghost, you can store it in your garage. Storing a ghost car in your garage will re-enable its object collision, but will disable collision damage. This makes the car effectively invincible, barring any shootouts.