The Stratum is a Zirconium four-door station wagon returning from the 3D Universe through GTA IV, GTA V and GTA Online, and it is due to appear in Grand Theft Auto VI. The rear of one can be picked out in the opening freeway shot of the first trailer, traveling through Hamlet near the Leonida Keys.
Vehicle data via GTA Wiki (Fandom), CC BY-SA 3.0.