Argent V missile
From Halopedia, the Halo wiki
Argent V missiles, can be used to destroy both surface and airborne targets. Though technically a strictly surface-to-air weapon, Argent V missile racks can be mounted to vehicles, thus allowing a greater range. Mendez had a rack of these missiles on his personal Warthog, back when he was a Chief Petty Officer while training the SPARTAN-II's on Reach. It is possible that it looks similar to the M12 LAAV only featured in Halo CE for the PC on multiplayer.
