In many of the large outdoor areas during the campaign, you will encounter both UNSC and covenant vehicles. In general, the vehicles of Halo 4 are much more powerful than those in Halo Reach. When you play alone, I usually do not suggest that you use smaller vehicles such as Warthogs, Ghosts, or Mongooses, but I highly suggest that you use larger vehicles such as Scorpions, Wraiths, and Mantises. When on foot, you can destroy covenant vehicles by stunning them with your overcharged plasma pistol and then hijacking them. There are no Promethean vehicles in Halo 4. All vehicles have unlimited ammunition, though all machineguns overheat.
Broad Sword : The Broad Sword is a UNSC bomber that is nearly identical to the UNSC Saber from Halo Reach. Just like the Saber, the Broad Sword is equipped with a heavy machinegun and rapid fire heat-seeking missiles. Even though it is a bomber, the Broad Sword is very maneuverable and has a powerful boost (just like the Saber), although it cannot perform evasive maneuvers. It can carry and deploy high explosives, such as the nuclear missile you use in the 8th mission.
You fly the Broad Sword in the first section of the 8th mission, though you do not use it to fight enemy aircraft. Instead, you must maneuver through many forerunner structures while avoiding fire from Promethean turrets. To avoid these turrets, you will need to boost past them, though this will make it much harder to turn. Therefore, you should stop boosting when making a tight turn.
Mantis : The Mantis is a bipedal vehicle equipped with a heavy machinegun on one arm and a rocket launcher on the other arm. The machinegun inflicts large amounts of damage and is capable of firing for a long period of time before overheating. It is incredibly effective against infantry and small vehicles, and it can destroy Wraiths and Phantoms with sustained fire. The rocket launcher deals high damage and can fire 5 rockets in short succession, though it takes a long time to reload. These rockets are great against heavy vehicles and aircraft, especially since they home onto enemy aircraft. If your machinegun overheats, you can use the rocket launcher to continue firing until the machinegun is ready to use again. Because each weapon is on a different arm, you can fire them at the same time.
Because the Mantis walks on two legs, it can move in any direction. For this reason, you can take cover and sidestep threats as though you were on foot. This high mobility makes surviving in the Mantis very easy, even though it does not have as strong armor as the Scorpion or Wraith. The Mantis is equipped with regenerative shields that help prolong its life. These shields have a much higher capacity than the shields of your armor, though they take much longer to regenerate. If your Mantis loses its shields, I suggest that you take cover immediately to prevent any damage to the hull (which does not regenerate).
Mongoose : The Mongoose is a fast, lightweight ATV great for transporting between areas. It does not have any firepower, although it does have a passenger seat from which a second player or an AI can shoot. Because of its limited firepower, I do not suggest that you use the Mongoose in combat situations.
Pelican : The Pelican is primary UNSC drop ship and it is used to transport infantry, weapons, and light vehicles. During the 6th mission, you are able to fly a Pelican for the first time in the Halo franchise. It handles very similarly to the Falcon from Halo Reach, but it has much more damage resistance and stronger weaponry. Use the bumpers to change altitude when flying, and hold the left trigger to boost. The Pelican can hover and move in any direction, so it is very easy to pilot. The Pelican that you fly is equipped with a heavy machinegun and a vehicle grade Spartan laser. It also carries an assortment of UNSC weapons which you can access after landing.
When you find yourself under fire, change altitude and fly side to side sporadically to make yourself a harder target to hit. When you use the Pelican in the 6th mission, you will only fight Phantoms. Fly to an altitude well above the Phantoms and shoot down on them from a distance with your machinegun turret. You will have a much easier time hitting the Phantoms from above because their top is much larger than their front. Phantoms have a hard time shooting upwards, so you will be safer if you keep a high altitude. Use your machinegun because it has a longer range than the Spartan laser.
Scorpion : The Scorpion is the primary UNSC tank, and it is the most powerful land vehicle that you operate in Halo 4. It has a very high damage resistance and it is equipped with a very powerful cannon. This cannon fires explosive shells that can destroy almost anything in a single shot and can destroy a Wraiths in two shots. On impact, the shells explode with enough power to kill an entire group of infantry, so the Scorpion can easily handle any type of threat. It also has a machinegun on the front that a second player or an AI can operate. This turret helps prevent infantry from approaching the Scorpion. The Scorpion's only weakness is its lack of mobility; it moves and turns very slowly, so you can easily become overwhelmed if you are not careful.
The Scorpion cannot take cover due to its poor mobility, so you instead must kill the enemies before they can damage you. Luckily, the main cannon is incredibly accurate, so you can usually pick of your targets from far away. Notice that the cannon shells travel slower than in Halo Reach, so you will need to lead your enemies if they are far away. When you are fighting Wraiths, engage them from a distance as well. However, Wraiths have a very long range, so they can hit you from a distance as well. Therefore, you should constantly move perpendicular to an enemy Wraith so that it cannot hit you (its cannon travels very slowly and the enemies are not smart enough to lead you.)
Warthog : The Warthog is a medium sized UNSC scouting vehicle, similar in size to a modern day Jeep. The driver of a Warthog does not control any weaponry, but each Warthog has a rear turret that allows a second player to provide firepower. When you are playing alone, I do not suggest that you use Warthogs because you must rely on a UNSC ally to either gun or drive. If you gun, the AI will drive you right into the middle of the enemies and will get you killed almost immediately. If you drive, the AI will only start shooting when you get very close to any enemies. This will force you to rush into the enemies, which puts you in much more danger than necessary. I instead suggest that you fight on foot or hijack a covenant vehicle. If you are playing on Co-op, you may wish to use a Warthog. Allow one of the UNSC allies to enter the riding seat of the Warthog if you only have 2 players.
There are 3 subcategories of Warthogs that are differentiated by their different types of turrets. Other than their turrets, these Warthogs are identical. The standard Warthog is equipped with a machinegun turret that is slightly more powerful than the UNSC mounted machinegun. The fast fire rate of this machinegun makes it great for killing infantry and light vehicles, and with sustained fire, you can destroy heavy vehicles and aircraft as well. The Gauss Warthog is equipped with a Gauss cannon, which is the vehicle equivalent of a sniper rifle. This cannon is incredibly accurate and has an incredibly long range, though it fires relatively slowly. It deals enough damage to easily kill vehicles from a distance, though up close, a large group of infantry can easily overwhelm you. The Rocket Warthog is equipped with a rapid fire rocket turret. Every time you pull the trigger, the rocket Warthog fires six rockets over the course of around 2 seconds. This is my least favorite turret because you must always shoot 6 rockets at a time, making it very hard to use. Furthermore, these rockets are very inaccurate, travel slowly, and deal little damage. Most infantry will dive out of the way of the rockets, and it requires many rockets to destroy vehicles. My personal favorite Warthog is the Gauss Warthog because it allows you to pick off enemies from a safe distance.
Banshee : The Banshee is the primary covenant aircraft, and it is the only covenant fighter seen in Halo 4. It is a very maneuverable aircraft; It can boost and perform evasive maneuvers to avoid threats from the ground and air. If you boost while performing evasive maneuvers, you will perform them faster. The Banshee is equipped with both a fuel rod gun and dual plasma turrets. You can swap between these weapons by pressing y. This fuel rod gun is great for killing infantry and small vehicles on the ground and for damaging enemy Banshees. The plasma turrets are best for finishing off damaged Banshees.
From the ground, it is nearly impossible to kill enemy Banshees unless you have heavy weapons like a Spartan laser or an incinerator cannon. Therefore, you will need to use a Banshee to kill enemy Banshees. In every area with Banshees during the campaign (specifically, the 2nd, 3rd, and 6th missions), you have access to an unattended Banshee. Enter this Banshee and fly at a high altitude away from the infantry on the ground to engage the enemy Banshees. They will usually fly directly at you while firing their plasma turrets, and they will sometimes fire their fuel rods as well. When they are flying directly at you, you can easy hit them with a fuel rod. Then, follow behind them and finish them with your plasma turrets.
Ghost : The Ghost is the most maneuverable land vehicle in Halo 4. It hovers roughly a foot off the ground, allowing it to move in any direction, unlike UNSC vehicles with wheels. It is equipped with a long lasting, powerful boost that allows it to easily escape threats and ram infantry. On the downside, the Ghost only has plasma turrets and it has very little damage resistance. You can kill infantry with sustained fire from the plasma turrets, but they are practically useless against other vehicles. Therefore, I mostly suggest that you use the ghost for transporting between areas during the outdoor missions.
When you are on foot, it is easy to overcome enemy Ghosts by hijacking them. Wait in cover with your plasma pistol ready until the Ghost approaches your position. Once it comes close to you, charge up your plasma pistol and quickly pop out of cover to stun it. Then, sprint over to the Ghost and press x to hijack it before the EMP wear off. You can now finish off the driver with the Ghosts plasma turrets. However, I do not suggest that you continue to use the Ghost for combat; Instead, park it far away from the enemies so that no one will reenter it and continue to fight on foot. You can then enter the ghost later to transport to the next area.
Phantom : The Phantom is the primary covenant drop ship, and it is capable of carrying a large number of infantry and up to two Ghosts or one Wraith. The Phantom is equipped with a concussion turret on the front and two grunt operated plasma turrets on the side. Therefore, you should usually take cover when Phantoms arrive to avoid their fire. Once they leave, immediately begin picking off the infantry they deployed before they can take cover.
Most Phantoms in the game are invincible, so you should not try to destroy them. However, in the 6th mission, you engage many enemy Phantoms with a Pelican. These Phantoms are not invincible and they are equipped with rapid fire concussion turrets that fire more than 3 times as fast as the standard ones. Engage these Phantoms from a high altitude and destroy them with your heavy machinegun.
Wraith : The Wraith is the covenant tank and artillery. It is equipped with a powerful cannon that fires arcing plasma balls. This cannon has an incredibly long range and deals immense damage and splash damage, which makes it highly effective against vehicles and infantry. Wraiths are also equipped with a plasma turret operated by a second individual, which helps prevent infantry from hijacking the Wraith. Because the Wraith's cannon arks, you need to fire well above far away enemies so that the trajectory hits them. Like Ghosts, Wraiths hover over the ground, so they can move in any direction.
To destroy Wraiths on foot, you will need to plant a grenade in them. However, the plasma turret is always operated by an elite (unlike in Halo Reach), so you cannot easily snipe him out of the turret. If possible, come up behind the Wraith and EMP it with an overcharged plasma pistol. Sprint up behind the Wraith and board the back by pressing x, then press the left trigger to plant a grenade. If you cannot approach the Wraith from the rear, you will instead need to snipe out the elite operating the plasma turret before you can approach it. If you have a sniper rifle, kill the Elite with two headshots. Otherwise, shoot him many times in the head or body to remove his shields, then finish him with a headshot. You can then stun the Wraith, board it from the front by pressing x, and plant a grenade to kill it.
You may want to hijack enemy Wraiths in order to use them. Perform the same steps as though you were going to board the Wraith from the front, but instead of boarding it by pressing x, jump on top of the Wraith. Walk forward until you are standing on the plasma turret and a dialog prompt says "press x to enter turret". Press x to enter the turret, and the elite will get out of the Wraith. Kill him with the plasma turret, then enter the Wraith.