DDA does not manage any save backups for you.
If your vehicle is saved, it will be in a file in the saves/yourgameworld/maps directory. I recommend searching that directory for the name of your vehicle if you know it. If you don’t, you can still search for the string “vehicles” to find all the discovered vehicles. You can also search for the id of rare items that you know are in your deathmobile, or names of named items if there are any.
Note items on your character will not help since the vehicle and the player are saved separately.
If it’s a deathmobile it will likely have a huuuuge definition, so you might just want to find the biggest file in there and check for it.