Halo 5: Guardians' next update, "Hog Wild," launches on Tuesday, 343 Industries announced yesterday, and though it will not deliver any new maps for multiplayer it does provide some additional vehicles, per its namesake.
That would reference the Warthog, the 4WD ATV that's been a fixture of the series going back a decade. Four of those vehicles, ranging from the "Rally Warthog" to the "Vespin Rocket Warthog" will be available in REQ drops beginning May 31
A bunch of other items are available; you can see them on Halo Waypoint. This is a free title update.
Additionally, the game is getting a "hybrid weapon scope" (pictured). However, some of the features originally promised for this updat — the second in May for Halo 5 — are being held over until the update that delivers Warzone Firefight.
Tellingly, 343 said the "Halo Wars 2 team is anxiously gearing up for E3," which confirms what most already knew or suspected.