The ultimate vehicle, my favorite vehicle; The Mongoose. Here's what I use with my friends to totally own with a mongoose.

One of the things we do is travel. This works especially well with sniper. You get on the mongoose and then the sniper gets on the back. After that you take him to one location and hide the mongoose. Stay close to your sniper and when he gets a couple of kills get back in the mongoose and go somewhere else. This technique works very well on Valhalla and Sandtrap. Also you can just travel to anywhere pretty quickly. The mongoose is pretty durable and fast.

The second is Rocket Raiding. This is pretty easy but just don't get too close to your target. First get a rocket launcher. Jump on the back of a mongoose. Once you see the enemy get close but not too close and fire twice. While you're reloading escape. We got this technique from the level, "The Storm". Works good in most maps.

The third which is pretty hard but simple is a Driveby. Get a shotgun and hop on the back. For this your driver needs to get pretty close to the enemy. Once he's in range of a kill, just pull the trigger.

The last is Annoy, Aim, Fire. What you do is have a sniper find an enemy. Ride by the enemy honking your horn over and over. This should get their attention. What usually happens is the person stands still to fire at you. While he's standing still just let your buddy get a headshot. Doesn't always work, especially when you get higher and higher in rank/level.

Anyways, hope this helped and I'll probably update it later with more techniques.