From Halopedia, the Halo wiki
This article documents its subject as it pertains to the gameplay of the Halo games, rather than the lore.
Universe and lore
The HuCiv HC1500 is the most comparable to the ONI Van in terms of performance, size, and other functionality, especially the variant in the Halo: Reach campaign which has a built-in compartment in the rear.
The ONI Van is a slow moving, two-seater. It has a horn and makes a beeping sound as it reverses.
List of appearances