I use mine to say hello to cows.
When a passenger of foot hove in view, how else are you supposed to tootle him with vigor?
On the nose, Old Bean. Otherwise one becomes like the cat in the adage.
Horns make your car go faster. Just ask any driver from Bangkok or Saigon (but nobody in those cities seems to road rage - it’s odd).
If you use your horn a lot and you have a red car, you’ll be the fastest thing on the road. 
Therefore what I am going to say is a confession. Luckily, the statue of limitations will protect me.
My wife insisted on buying a used Jaguar (that in itself is not too smart.). We did not test the horn, but later found out it did not work. To fix the problem would have cost $600 and so we never fixed it. :o Because of that experience I can testify that not having a horn can put you in some scary situations. The worst I remember was someone backing out of a parking space and not seeing me…(until the last minute). I know it could have been worse and I’m only making this post in case the OP hasn’t gotten the message yet. The fact you only use the horn once to avoid danger; makes having the horn worthwhile
But only if it has a stripe and/or flames painted along the side. Everyone knows that the stripes make you more aerodynamic, and the flames give you extra thrust, just like a rocket.
Chronos you are forgetting something. Everyone knows that bolting a fat 5" diameter exhaust onto your normal pipe will boost the cars performance by at least 25%.
Oh and regarding horns: The horn is there to warn other road users of your presence. I have used my horn numerous times to save myself from a collision. One time I was in the left lane, moving slowly, the guy on the right didn’t see me and started to move left. By using the horn he became aware of my presence and stopped moving left. Horns are very useful if used responsibly.
And, around here, a huge marque logo on the rear window (gigantic Honda curvy “H”) and the name of your car repeated in very large stick-on letters, substituting numbers if you run out of letters – CORO11A. (Honestly, one of my neighbours did this.)
I found a pleasant toot of the horn is the best way to show your appreciation to the person who’s working on your engine.
Don’t forget the spoiler. Adding a spoiler reduces acceleration time by half a second for each ten miles per hour. :rolleyes: 
That’s a darned useful statue! I thought only the Statue of Liberty did that! 
When I was a kid we had a cat that liked to sit on the front wheel of the car after it had been running - nice and warm from the engine, then it decided to climb inside the engine bay! So to prevent cat Vs fan belt nastiness it was standard practice to toot the horn before starting the car - I think there only a couple of actual “Toot!” - “Clang!” - “Meow!” incidents before the moggy got the message.
A friend bought a second hand motorbike, Sakkacrappy 900 or whatever, nice and fast - he was very pleased with it. Rode it for quite a while until one day he needed to use the horn - no sound - so he strips off the front faring to fix it. Turns out there is no horn to fix and there’s no horn because there’s no bracket to fix the horn to. The guy who’d sold him the bike had dropped it in a big way at some time and had welded the front end up himself - he’d even gone to the trouble of making fake bolt heads out of wood and spraying them up! :eek:
I thank everyone for their replies, but apparently I didn’t make myself clear. What was the original purpose horns were installed on cars? Did they not make an appearance until enough model-T’s were on the road to cause problems, or were they added to enhance engine performance as TheLoadedDog mentioned?
Thanks again.
My Hispanic neighbors seen to think of it as a simple door knock. Pull up at 5a.m. blow your horn until your fellow workers come out for their ride. I want a a bill passed that all white vans must have their horns removed.
To notify those around you that you`re horny.
Even early cars were fitted with horns to warn other road users that they were around. Don’t forget that there were horse-drawn vehicles before there were petrol-driven ones – the roads were pretty busy long before they invented the car.
In the early days, cars were thought to be dangerous things in themselves. They sometimes blew up and their noise scared the horses. So there were very strict speed limits and a man with a warning flag had to walk in front of them.