[jakobe]

Preventing DUI is a difficult problem. A much easier problem would be to prevent speeding. Put a GPS in every car that prevents the car from driving faster than the speed limit. All the technology exists, and this would doubtlessly save lives, but somehow I doubt anybody would pass the required laws.

[freehunter]

I always wonder why we make cars that can go so fast. Even my car with a 1.4L engine making 100 HP can easily do 100mph, even though there's almost no place in the US where that's legal, and no place in my state where it's legal. The fastest speed limit in my state is 70mph. Why not speed-limit cars to 70mph by default, with an option to disable this limiter in a controlled fashion if the person wants to go out on a racetrack where these speeds are legal?

There are obviously arguments in favor of personal liberty that would make some people uncomfortable with this, but they shouldn't be. No one should be. If the speed limit on the road is 70mph, there is no reason for your car to be doing more than 70mph on the road, period. I don't care that you want to pass a vehicle that is only doing 69mph, you'll either lower your speed or pass them at 1mph (which, at least in my state, is also illegal. To pass someone, they must be doing at least 5mph under the speed limit, and you can't break the speed limit in order to pass someone).

Now, it wouldn't help in this situation, but it's something that's always bothered me. As we make better and better performing entry-level cars, we can't change the laws of physics. 90mph isn't unheard of as a common cruising speed on a road where the minimum speed limit is 45mph. That's just stupid and dangerous.

[wtracy]

I always wonder why we make cars that can go so fast.

If you are actually questioning why car engines have enough power to do that in the first place: An engine capable of hauling a heavy load uphill at the speed limit is capable of exceeding the speed limit on a flat surface. Ditto for an engine capable of accelerating quickly to perform a merge in a short space.

If you are asking why cars don't come with interlocks preventing those kind of speeds: Because they're not required, and they're not a marketable feature.

[freehunter]

I understand more power. What I was trying to get at was "why is it not required to speed limit cars to 70mph". That's common with semi trucks; the trucks at my company are speed limited to 65mph (the semi speed limit here).

[jcromartie]

Speeding is not involved in the majority of fatal accidents.

[freehunter]

Maybe, maybe not (I don't know), but two things come to mind:

1) Speeding is illegal. This is a law that is broken every day by millions. Obviously the law and the punishments aren't working as a deterrent, and the next steps usually involve control rather than deter.

2) Do you know how reaction time and braking time change for every 5mph faster you're going? It might not make you cause an accident, but it sure doesn't help trying to avoid an accident.

[jakobe]

That is a pretty bold statement. Pretty much all fatal accidents I've heard about involved speeding in some way. Now, anecdotes aren't reliable, so do you have some numbers to back up your claim?

[overdrivetg]

"Q. Aren't most traffic accidents caused by speeding? A. No, the National Highway Traffic Safety Administration (NHTSA) claims that 30 percent of all fatal accidents are "speed related," but even this is misleading. This means that in less than a third of the cases, one of the drivers involved in the accident was "assumed" to be exceeding the posted limit. It does not mean that speeding caused the accident. Research conducted by the Florida Department of Transportation showed that the percentage of accidents actually caused by speeding is very low, 2.2 percent."

from http://www.motorists.org/speed-limits/faq

Q: Is the National Motorists Association a reliable source for this data?

A: I did the 30 seconds of work to go and Google this, go find your own stats if you don't like mine.

[jakobe]

> 30 percent of all fatal accidents are "speed related"

Almost all accidents are "speed related". Very few accidents happen with cars standing still.

[derekp7]

I would love to have a device like that, kind of a reverse cruise control The only times I've gotten speeding tickets is when I was unaware of a drop in the speed limit. Maybe something that combines GPS, plus a dash cam that recognizes road signs (so that it can pick up construction zones, etc).

Only one major problem with this -- many areas are funded in large part by speeding tickets. If it is impossible for a car to speed, what will these areas do for revenue?

[xbonez]

Agreed. My $100 Garmin GPS tells me what the speed limit is, an what speed I'm doing. I've often wondered why this wasn't just built into cars to ensure they throttle lock at the speed limit.

[gre]

That would be extremely dangerous.

[freehunter]

Why? What's the situation where you would need to go faster than the speed limit?

[wtracy]

Passing another vehicle comes to mind.

I'm not sure I would call that "extremely dangerous", though.

[freehunter]

Breaking the speed limit to pass another vehicle is against the law. At least in my state, you can't legally pass unless the other car is going 5mph under the speed limit, and then you can only pass at the speed limit, not over.