I found a bug, that I just fixed: when editing vehicle info, the owner preciously set was lost.
I don't know since when there is this bug, but it is annoying, since possibly some owner that were linked to vehicles were accidentally removed.
If you notice one missing, don't hesitate to mention it in the comments on the site, or here.

edit: I restored a few by comparing the list of owners with previous copies of the database, there may still be some missing.