Same thing has happened to me a couple of times. Usually I just reload an earlier save, but this time it happened just as I escaped from the Wolf Spider in the Spider Den Ants Nest. Game Crashed, and on reloading, my buggy is no longer there. I can't recall it, and it isn't in the nest back at my base.
This is the first week of early access, so of course we should all expect these things. I don't mind at all usually. But I really, really don't want to have to go back through that Spider Den Ants Nest.