The Phoenix is an Imponte two-door muscle car with roots in the 3D Universe that carried over into GTA V and GTA Online, and it is due to appear in Grand Theft Auto VI. It has been spotted repeatedly in pre-release material: passing a flipped SUV in the first trailer, driving through the September 2022 leaks, and showing up in the second trailer and an official Port Gellhorn screenshot.
Vehicle data via GTA Wiki (Fandom), CC BY-SA 3.0.