There are many opportunities throughout the Halo Reach Campaign to pilot a variety of vehicles. However, I usually do not suggest using these spray on bedliner in combat for a few key reasons. First, unlike when you are on foot, you cannot use cover in a vehicle. Second, when playing on legendary, most vehicles do not provide enough damage resistance to overcome this lack of cover. The combination of these two things makes it more dangerous to use a vehicle then to fight on foot. Third, most vehicles have limited firepower and accuracy, so using a DMR and plasma pistol combination kills enemies faster and from a longer distance. Finally, enemies will stun your vehicles with overcharged plasma pistols, and since half of all Grunts, Jackals, and Skirmishers have plasma pistols, this happens often. These reasons combined make using vehicles impractical on Legendary. Therefore, I suggest only using them for transportation.
Some vehicles have passenger seats, allowing an ally to ride in the vehicle. When a passenger enters a vehicle, they are allowed to fire and swap weapons normally, providing the vehicle with extra firepower. This is useful for transporting multiple players as well.
Overcharged plasma shots allow you to EMP banshees and all covenant land vehicles except scarabs, allowing you to jack or kill them easily. Once you jack a covenant vehicle, I generally suggest not using it for combat. Drive the vehicle away from the enemies so that they will not enter it. If possible, leave it near the main path so that it can be used for quick transportation in the future.
Banshee: The banshee is a very maneuverable and quick aircraft with double plasma turrets and a fuel rod. Banshees also can perform complex maneuvers, known as banshee tricks. By pressing the left bumper and tapping the right joystick left or right, the Banshee will perform a barrel roll. By pressing the left bumper, holding the right joystick to either side, and holding the left trigger down, the Banshee will perform a 180 degree flip turn, very useful for turning to face enemy aircraft from behind. A combination of these maneuvers and boost (left trigger) allow you outmaneuver enemy aircraft and homing enemy projectiles. When entering a banshee, it will default to the plasma turrets, good for killing infantry and finishing off injured vehicles. To change to the fuel rod, press Y. These missiles deal high amounts of damage, lock-on to vehicles, and have high splash damage so are useful against both infantry and vehicles. Banshees can also be operated in space.
In most missions, you cannot jack banshees. Enemy banshees most commonly use plasma turrets so do not pose a large threat. However, if they become too much of problem, you can kill them with mounted machine guns, Spartan lasers, rocket launchers, and scorpion shots. However, in the 3rd rally point of the mission Tip of the Spear, you are able to jack downed banshees, earning you an achievement. First, stun them with an overcharged plasma pistol and start charging another one as you sprint to the crash site. Once you arrive at the crashed banshee, use the second plasma shot you have been charging to keep it stunned. Once you are next to the banshee, press x to jack it.
Ghost: The ghost is the fastest and most maneuverable land vehicles, with relatively weak weapons but great ramming capabilities. This makes the ghost perfect for transporting between fights during outdoor campaign missions and boosting past enemies. If you hit any enemy not using armor lock at full speed while boosting, it will instantly kill that enemy.
To jack a ghost, stay in cover and charge a plasma pistol as it approaches you. After it gets close, run out of cover and jump around a lot to avoid the plasma bullets. Once you achieve lock-on, stun it and jack it. Ghosts are driven by Grunt heavies, Elite minors, and Elite majors, although any other types of Elite, Brute, or Grunt often enter unattended ghosts. Jacking a ghost operated by a Grunt will kill automatically kill the driver, but jacking a ghost operated by an Elite will only remove around half of an Elite’s shields. If you jack a ghost driven by an Elite, boost away so the Elite cannot jack you. You can also destroy a ghost by shooting the motor, located behind the left wing. Five DMR shots will cause it to explode, destroying the entire ghost.
Phantom: Phantoms are the main drop ship for the covenant army, and are most often seen dropping enemies before a fight. A phantom can carry many infantry as well as one ghost, revenant, or wraith on the bottom. Every phantom has a concussion turret mounted on the bottom, and also has two Grunt operated plasma turret on either sides. Phantoms can also be operated in space, in which case they are sealed and armed with heavy plasma cannons.