This also seems to be the case for other vehicles that supposedly have the horn option. Such as the civilian offroad and the Ifrit.

can confirm this.
all 3 hunter versions plus all 3 ifrit versions.
does not matter if it's in editor or multiplayer.

Same here. I had the opportunity to try multiple times and never worked (SP and MP).

Every Vehicle doesnt have a horn sound yet. i dont think they finished the vehicle functions totally yet, like the fullscreen gunner seat instead of pip, which i have turned off because of lag

@CranberrySauce press 0 on your Numpad or right mouse button or whatever your optics key is.

Confirmed.

@Astaroth I've checked - it's resolved. Ticket can be closed.