Since 1.03 released, there has been a bug that when the server starts, when the vehicles are loaded, sometimes they are in a new position than before. If the new position change results in them clipping into any form of geometry, they are often damaged or destroyed, sometimes even flung hundreds of meters into the air or away from original position.
This may have been reported before, but I am making a ticket as all the talk I've seen across various medias have mostly been people claiming vehicles disappear on restart, which isn't an accurate description of what is happening. Filing this ticket just in case the cause of the issue has not actually been properly reported before. I have tested and the issue is still present on 1.05 Experimental.