Überchassis
From Halopedia, the Halo wiki
Uberchassis is the name for the car that's sitting on the pedastol in the offensive base of Terminal, as well as in various places in Outskirts and Metropolis.
With the mod kit its possible to drive the Uberchassis as shown in this video:
Note Über is German for super and chassis comes from the Latin word for case, so the Überchass could also be known as the "super case".