Obviously, the sound of an internal combustion engine, just like we are all used to.
Doesn’t this remind you of the laws of 100 years ago that required a man to walk in front of any “motor-car”, carrying a lantern at night and waving it side-to-side, to warn everyone to get out of the way? Both are born out of unfamiliarity. Isn’t every child taught to look & listen before crossing the street? This one didn’t.
On a slightly serious note, if we ever do see a lot of fully electric or fuel cell vehicles on the road, there could be a market for this kind of thing. A company could sell a speaker of some sort that you hang behind the grille, allowing you to give your car engine sounds. The sound effects would change appropriately with the speed of the car. And, you could have a little control to pick a sound-of-the day: starship hum, V8 growl, diesel rattle, steam-engine pocka-pocka-hiss, horse hooves. It would be another way to give your car personality, and the first guy to market it could make a ton of money. If (big if) the internal combustion engine goes away, that opens up a whole new avenue for people to [del]annoy the hell out of me[/del] express themselves.
Since I’m a die-hard railfan, mine would sound like a diesel locomotive. Fortunately for me, there’s already a market for sound effects for model railroaders…
I am sure these already exist. On MTVs Pimp My Ride they installed such a device on a car where you could make it sound like a Porsche, a Ferrari or an American muscle-car. They hook it up to your throttle and it sounded quite convincing.
Apparently he was hit because he rode his bike into the path of the car.
Damn. Once again, I invent something too late. OK, so I have this idea for a pocket-sized device on which you can store… music! Wouldn’t that be great?!
Sigh. Maybe I should pay more attention to what’s going on around me before I invent anything else.
Tell me about it. When I was in electronics school, I designed a car horn that used samples. It had a selector switch and and a microphone and you could record your own samples, such as me yelling, “Get out of the way!”
Plus, my “invention” was also invented by you in Post 2 in this very thread. So I’m even more oblivious than I thought a minute ago. I usually avoid smileys, but this calls for a :smack:
I still lay claim to the idea of using horse hooves sounds, though. That one was all me.
Well, you’re all missing the boat. They should make the sound of the flying cars in The Jetsons, of course.
…as heard here: Jetsons intro.
That would be perfect.
Chitty-chitty-bang-bang
Or some sort of agonised screaming sound
Oh, how about the sound of a tie fighter from Star Wars?
ETA: How the hell are you supposed to spell that anyway? It just gave me the mental image of a kid getting all tangled up while trying to tie a Windsor knot.
I was going to post this a couple days ago for Tuckerfan, being as this was a weird calliope car. Click the image to see it at a good size. Enjoy the car.
TIE Fighter (stands for twin ion engines)
I don’t want my car to make a noise, but I have to admit that the popcorn sound would be kind of amusing.
And do get me started on what my reaction would be if the car made a farting noise. I’m sure many of you can imagine. 
Apparently he was hit because the driver of the car wasn’t paying attention to pedestrian traffic.
Could make it sound like gerbils running on a wheel.
Related stuff:
The Fisker Karma already comes with that option
The Virtual Motor System “Fake engine sounds for real posers”
If you don’t look you could just as easily step into the path of a bike or someone on rollerblades if you step off the curb suddenly.
Ah, thank you. I still had my childhood impression that it’s because they were vaguely shaped like bow-ties.
(No, really, that’s what I thought when I was a little kid.)
Of course! The Wilhelm scream.
Actually, if I ever placed a noise produces in my Civic Hybrid, I think I would seriously consider the pacman noise.
wakka-wakka-wakka-wakka-wakka-wakka-…
Chicago’s even laid out on a grid!
If we are worrying about kids, I’d say we should make the car sound like an old-fashioned ice cream truck. That would get their attention 
Well sure. But the chances of death via rollerblader are just slightly less than that of being squished to death by a car.
I dunno. I hate the idea of adding more noise pollution, and I hate the entire concept of requiring “safety features” to protect people from their own carelessness, and I REALLY hate the idea of “cruisetones” even more than I hate the idea of ringtones, but natural selection does seem to be in play here. The environment (ie. “cars make noise”) has changed, and either we pick off the weakest of the herd who can’t grok that, or we alter the cars to fit the old rules.