Don't know whether it's because of my limited knowledge of the game mechanics or something else, but there is one case when my offroad suddenly disappeared after I took something from it and walking away (about 50 meters from it).

FYI,
this happens at night.
It is in MP mode ( I was playing w/ my friend)
My friend experienced the same thing but with a whole different stuff. In his case, it was his backpack that was vanished from the corpse of him after spawning.

Is it a glitch or a probable theft mechanic?