You can (de)activate the tabbing of the current vehicle with Ctrl + T to “park” vehicles.
With Shift + Ctrl + T you can activate tabbing again for all your vehicles.
In Multiplayer the parking state is only set for yourself.
The state is saved in single player and in multiplayer.

Github-link: https://github.com/VertexDezign/ParkVehicle

Changelog:
1.1.2.0:
* Fixed: Prepared for the removal of the game's deprecated getUniqueUserId() function. The id your parked states are saved under is now stored in modSettings/parkVehicle.xml, so they are kept
* Fixed: Parked vehicles are no longer auto-unparked when another player moves them. Only driving the vehicle yourself (or the vehicle it is attached to) unparks it
1.1.1.0:
* Fixed: Vehicles the game marks as non-tabbable (car washes, conveyor belts, pressure washers, ...) could still be tabbed into, and Ctrl+T had no effect on them, in worlds previously played with version 1.0.x. Such savegames are now repaired on load.
1.1.0.0:
* Added: Auto-unpark a vehicle once it has moved a few meters (optional, toggle in General Settings)
* Added: Cycle through parked vehicles with Ctrl+Shift+Tab, bypassing the normal Tab restriction
* Added: Reposition the park icon via horizontal/vertical offset fields in General Settings
* Fixed: Vehicles the game already makes non-tabbable on purpose (e.g. car washes) are no longer forced into the Tab cycle
* Fixed: The parked state is now tied to the game's own unique player id instead of your player name, so players sharing a name no longer share parked vehicles (existing installations keep their current id)
* Fixed: A dedicated server no longer writes a redundant entry into every vehicle's saved parking state
1.0.1.0:
* Fixed: renderOverlay is only allowed in 'draw' callbacks.
* Added: Turkish translation