you need to go into object mode and then add an armature. Where you want the people to sit you name it mount0, and place it where you want the player to sit. Add more and name them mount1-mountwhatever for passangers.
Mount0 is the driver, i'm not sure if you need to name the actual object mount0 but i do anyways :3 The actual thing that you need to be named mount0 is the bone, i was having real difficulty with this and then finally solved it(thanks to racer).
You need to select the armature and then go into edit mode, then select the bone in the middle, not the little balls. Then press n to name and instead of where it says object:mount0, rename the part that says bone:bone. And call it mount0.
Do this for all of your other armatures, if you need wheels for your vehicle they're called hubs.(hub0,hub1,hub2,hub3) And again name the bone, not the object, though i like to name the object too(as i said above) just cause when i select it i dont need to go into edit mode to see which one it is.
Parent the armatures to your detail32, if you don't know what that is read the bottom of this:
http://returntoblockland.com/wiki/index.php?title=Blender_Tutorial#Step_One:_Making_Parents
