Vehicles are used to traverse the large playfields in Tribes: Ascend more quickly, or grant additional firepower. To get yourself a vehicle you need to visit your team's Vehicle Station (Capture the Flag & some Capture and Hold maps only), and purchase one with your game credits.
Once purchased, the Vehicle station will begin to glow and your vehicle will spawn, you will automatically be teleported to the drivers seat once it's ready.
While your vehicle is spawning you are granted temporary invincibility. However this only apply to the player, The vehicle can take full damage as soon as it's visible.
It is worth noting that any vehicle that is unoccupied by a player after about 60 seconds will self destruct. This is presumed to help ease vehicle caps being affected by vehicles that are lost in a difficult location, such as on the outskirts of a map or within the enemy base.
The Grav Cycle is a vehicle with motorcycle-type roots. A second player can ride the back and use their weapon. It is exceptionally fast and useful for chasing flag runners. The vehicle is armed with an 8-round explosive projectile gun, with a high rate of fire and a long reload time. The gun is placed at a very low position on the front, making it hard to hit enemies on flat ground.
The Shrike is a flying vehicle. With default configuration, left-click fires the Shrike's primary cannon, which has a four-round magazine. Right-click uses the afterburner, which provides a speed boost in-flight. In contrast to previous Tribes games (Tribes 2, specifically), the Shrike cannot fly right or left, but the afterburner still doubles as a vertical jet.
The Beowulf is a tank-like vehicle. The primary cannon does significantly more damage on a direct hit than with splash damage. Like the other vehicles it has a boost, but instead of making it accelerate faster it makes it turn faster; which is a great bonus if someone is speeding by you with your flag. A player may switch between the main cannon and the gunner seat by pressing F1(Cannon)and F2(Gunner). A second player can enter the vehicle and use the machine gun on top of the turret.
These vehicles exist in the game files, but are not currently usable.
The HAVOC is a vehicle that is currently unused, but exists in the game files, and appears in the Tribes Ascend Trailer. It previously appeared in Tribes 2.
It appears to be able to carry 4 passengers and a pilot, however it is unclear if there is a spot for a tail gunner like its Tribes 2 counterpart. Although "Switch to Seat 6" appears in the games Key Bindings.
The HERC is a very large tank that exists in the game files, as an untextured model, and it is referred to by several unused audio files.
It is unclear whether it was intended to be player controlled, or an uncontrollable part of some new gametype.
Other than its massive size, it has nothing in common with the HERC of Starsiege/Earthsiege fame.