Well I managed to make some progress but things are still not quite there, my characters are able to enter/exit the vehicles but the vehicle movement doesn’t seem to be replicated to the other client despite the server actually carrying out the movement operations. If I make the players swap vehicles after having moved them the true(server) location suddenly updates on the client. WTF?!?!
If I set the vehicle as the default player pawn in a custom game-mode everything works perfectly which suggests there is still something wrong with the way I’m doing the possession.