the "CarHorn" doesn't have any ammo, thus the moron won't "fire" it
:-\
The "honk" sound ya can hear is the "drySound" of the weapon (emptyMag-sound).
I'm afraid ya need to play the sound, m8 :-\ but howsabout finding a way
to make the car "say" this sound.... there IS a "say" command...
But it prolly needs some more, maybe a copy of the sound in the mission folder or...
dunno really, haven't tried.
Hope this will push ya in the right direction anyway, m8