FBI Car - The FBI car featured in GTA III and GTA Advance. It was meant to return in the final version, but the idea was scrapped. It was similar to the Las Venturaspolice car, but had a different grille. The model was going to be featured in an unused cutscene. The model and a low quality texture still exist in the game and it can be turned into a drivable vehicle via use of modifications.
Fenton - Fenton is a beta vehicle that was scheduled to be in the final version of the game. It was cut for unknown reasons. It could've been be a cheap 4-door European compact car or a Luxury Executive sedan probably manufactured by Enus. This vehicle was also cut from Grand Theft Auto IV.
Float - The Float was a beta vehicle that was cut from the final version of Grand Theft Auto: San Andreas. Only its handling data exists. Its handling shows that would have been a slow vehicle, like a train or a parade float.
Idaho - The 2-door coupe featured in all other 3D Universe GTA games. It was cut for unknown reasons.
Roller - Another new vehicle. Nothing is known about it but its handling. It appears to be either a roadroller or a rollerskates. A GXT entry for the Roller exists.
Skateboard - A cut weapon in GTA: San Andreas but also a vehicle. It was cut during the development of the game and was planned to be introduced in the mission Madd Dogg's Rhymes. In the PS2 files, the HUD icon is the only remains. However, on the PC version it is a complete weapon that can only be found in one of the game's beta interiors. Nonetheless, the weapon will only appear if it is enabled in the game's files. If not enabled, it will be a Knife.
The Stinger was supposed to return but was replaced by the ZR-350. A model of it can still be found in the game files.