For vehicles, I'd like to see:
Human
Gauss Mongoose: Tittle says it all, a mongoose with a gauss turret attached to the back. Because of this, it moves a bit slower.
Heavy Hornet: Has the standard auto cannons on the front but also has four passenger seats and a machine gun in back (similar to the Scorpion turret in Halo 3, except less powerful).
Transport Hog: Same as the Halo 3 Campaign variant.
Grizzly: Has a double cannon that fires one round per 1.8 seconds (rotates between both cannons), and no machine gun (for balancing issues). Slower than the Scorpion (by a quarter).
Hawk: Equipped with a chin mounted light machine gun, and two weak lazers (0.8 as powerful as the Spartan Laser). Slower than the Hornet (by half).
Cobra: Has two light gauss cannons. They do half as much damage as show in Halo Wars.
Covenant
Heavy Ghost: Equipped with a fuel rod gun, and no boost function.
Locust: Fires a laser similar to the Sentinel Beam. In function, same as in Halo Wars, but the gun is substantially weakened.
Specter: Same as Halo 2, just with upgraded graphics.
That's all the vehicles I can think of. Also of note, is that all these vehicles I mentioned are to be used exclusivley in Campaign, and even then very sparingly. Peace.
~Hunter