Doozy
From Halopedia, the Halo wiki
The Doozy is a UNSC boat/snowmobile vehicle that didn't make it into Halo 2 and is seen in the Halo 2 Collector's Edition video. It ended up getting a chaingun in the back, and to man the chaingun, one had to sit in the nausea seat which faced backwards. Though the player would of only used it only minor times, such as Delta Halo and or New Mombasa.