No message right now, but it should be very noticeable as the vehicle starts turning while you move forward. I actually just couple days ago started a new multiplayer game with someone. It was working even with helicopters, although with that specific one i prefer to toggle snapping off.
How are you guys installing mods anyway? You should have a mod manager outside the game that manages the enabled and disabled mods, i don't even know how ingame mod-portal integration or something works. There isn't full support for it yet as far as i know. Check mods menu when game is just launched, from there the activated mods should be clear to see.
You may also need to click on "Sync mods" button for your save. When you check the saves list, it should list which mods are tied to that save.
