MGV

The Medium Ground Vehicle is a two-person car that came with the Digital Deluxe Edition. It is currently the only two-seat vehicle outside of Broken Peninsula, (*) though Red5 has said that other MGVs will eventually be available. 
The MGV 15,000 HP and causes significant damage to things it hits or runs over. Under level 15 or so, it can be used to effectively clear out camps of enemies in the open world, dealing little to no damage to either the vehicle or the passenger(s).
The owner of the MGV can enter as a driver OR passenger. It can carry one additional person in either seat, but only while the owner is also in the vehicle. If the owner leaves the vehicle unused for a few seconds, it will de-spawn.
(*) Since the original posting of this WIKI, Red5 has released an MGV called the TS-RC8 "Snowsquall" that is now sold in the Red Beans Store for 400 Red Beans.