[Overdrive]

This could be a programming thing as has been brought up in other threads, EvansBlue. It's probably possible for the dealers to de-activate the horn beeping that happens when the car is locked, but since you said you're getting no horn sound at all I wonder if your horn has kicked the bucket. Like you, I also didn't realize that the alarm used a separate horn from my "GTFO of my way" horns.

If your windows are down past a certain point I'm not 100% sure that the alarm's motions sensors will still activate. One would have to look into this. I'm also not sure if the alarm is tied to the glovebox and set to go off if it is opened when the car is locked from the outside.

It is possible for your motion sensors to still work with the top down, otherwise what the hell's the point in locking the doors? You just need to get the car to still do it. You can either buy a red clip that activates the mircroswitch in the windshield frame where your top latches when raised, or you can press in that switch yourself and hold it while locking the car to make the car activate its sensors. This way if someone reaches or leans in while the top is down it'll still go off. Without tricking this switch the car will not activate the sensors, but it's not like it can't be done.

You can also deactivate the alarm's motion sensors and still lock the car by giving a double tap to the lock/unlock button on the key, which will lock the doors but won't activate any sensors inside, in case you leave your girlfriend, pet, sibling, or anyone else in the car and lock them in.