There are 13 standard vehicles in Halo Wars, one that is only available in the special edition of the game, and one that is only available as a pre-order bonus. Just like weapons, each playable faction has its own set of vehicles.
UNSC Scorpion
One of the vehicles from the UNSC faction in Halo Wars is the M808B, which is also known as the Scorpion. This tank is outfitted with a high-velocity cannon, a coaxial or pintle-mounted machine gun, and titanium-ceramic armor-plating. It can carry four soldiers (in addition to the tank's crew) who can fire their weapons from emergency jump seats on the outside of the tank. Although the Scorpion cannot travel very quickly, its cannon has a quick rate of fire and is able to do significant amounts of damage. The Scorpion is also covered with thick armor, making it difficult for most weaponry to do any significant damage to it.Halopedia: M808B Main Battle Tank
Covenant Scarab
Perhaps the most powerful vehicle available to the Covenant is Halo Wars is the Type-47 Ultra Heavy Assault Platform, also known as the Scarab. Originally a mining vehicle, the Scarab is meant to assault heavily defended structures and barriers and to give quick unstoppable support for Covenant troops on the ground. It can also deliver Covenant ground troops to their destination through heavily defended areas. The Scarab can hold full squads of grunts and is equipped with a powerful plasma beam cannon at the front. It's also the largest known ground vehicle in the Halo universe.Halopedia: Type-47 Ultra Heavy Assault Platform
Halo Wars Vehicles
United Nations Space Command
M12 Light Reconnaissance Vehicle (Warthog)
"Flaming" M12 Warthog Light Reconnaissance Vehicle (Warthog) - Only available with pre-orders
M808 Scorpion MBT
Behemoth-class Troop Transport (Elephant)
Gremlin
Rhino
Wolverine
Cobra
Cyclops Exoskeleton
The Covenant
Type-47 Ultra Heavy Assault Platform (Scarab)
Type-32 Rapid Assault Vehicle (Ghost)
Type-25 Rapid Assault Vehicle (Chopper)
Type-25 Assault Gun Carriage (Wraith)
Honor Guard Wraith: Exclusive to the special edition.
Locust