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Why Do Speedometers Go To 160MPH?

by Lloyd Alter, Toronto on 10.20.08
Cars & Transportation (cars)

speedometer image

A great way to get all the testosterone soaked hard core engineers who hate whining environmentalists wound up is to say something nice about Jimmy Carter, but here is another eminently sensible thing he did: He capped the maximum speed on speedometers in cars at 85 MPH.

Tom Vanderbilt thinks it affects the way we drive. "even knowing that these numbers bear little relationship to reality, we’re affected by the visual display. No matter how fast we drive, the needle is always less than halfway up the dial, indicating there’s still plenty of room for acceleration. That remaining space may even goad us into testing the limits by going faster."

Vanderbilt continues: "Capping the speedometer would remove a theoretical and illegal max to test on public roads. Influenced by the so-called anchoring effect, people are induced to eat more when portion sizes are larger and to drink more when the range of beverage options is increased. (Many consumers eschew the biggest and smallest drink choices at fast-food restaurants, so companies have supersized their “large” choice, thus making the “medium” more palatable, even though it’s bigger than ever.) In the same way, the value of 160 on my speedometer has been shown to influence decision-making."

Of course, Ronald Reagan removed the regulation immediately. More at Tom Vanderbilt's blog How We Drive.

More on Jimmy Carter in TreeHugger:
Admit it: Jimmy Carter Was Right
Eco-Tips: Jimmy Carter's Sweater
55 MPH : It's time to bring it back.
55 MPH Movement Is Gaining Speed

More on Tom Vanderbilt in TreeHugger:
55 MPH Movement Is Gaining Speed
The Inalienable Right to Speed

Comments (19)

A better question that has been discussed hear before:
Why don't cars come with an mpg gage?
Not having a direct feed back has got to be worse than some notion of "I can speed forever!"

jump to top Jeremiah says:

What would all the motorheads look forward to when they get in there Mustangs?

jump to top Bob says:

i've been saying this for years. in nyc where speed limits are suggestions rather than law. conserving gas and doing the speed limit is dangerous. cars are flying by you, what we need are gps enabled systems that work with our vehicles to regulate how fast we can travel.

jump to top herman says:

Great point.

Here's another thought...

Why are cars designed to exceed speed limits? I mean, if the authorities really wanted to eliminate speeding, they'd manufacture cars that could go no faster than the maximum posted speed limits.

Designing a car in this way would also be great for the environment.

(And you thought your comment was contraversial! lol)

jump to top Lee says:

Why is it illegal to drive above the speed limit, but car companies can make a car which can reach double the speed limit? Jimmy was right, lower the speedometer, and put a governor on all cars sold. Of course people will find out how to modify it, but with a yearly inspection most people would forgo the effort so that they can illegally speed.

jump to top Andy says:

Wouldn't you think that some lawyer would have argued that automakers are liable for accidents where speed was an issue when speedometers include speeds that go beyond the handling limit of their vehicles?

I remember in the 70's hearing about souped-up VW Bugs -- when you got somewhere over 90mph the front end would lift up due to aerodynamic issues. So even though the rear wheels could push you faster, at some point you lost steering control.

So if VW knew that, but installed speedometers that went up to those speeds anyway, if some unfortunate fool went that fast and was in an accident, you'd think there would be an opportunistic lawyer ready to say that VW was at least partially to blame.

(If such a case was filed, I'm guessing that the automaker settled the case and part of the settlement included some sort of "don't talk about this to the media" clause.)

:-)

jump to top Foraker says:

I found, by comparing my spedometer to a gps, that I was traveling slower than what the needle was saying.

I wondered if this was a purposeful design to keep people from actually doing 100mph when they were actually doing 85mph....dunno.

Another argument on the spedometer range...
with a 0 to 160mph meter....I would think it was easier/safer to glance down at your speedometer and see it's position as opposed to it's reading and know how fast you were going. Perhaps a "straight-up" indicator is good enough to know that you are going the speed limit.
Once again, we are visual creatures....we process motion and lights first, before we are able to think/analyze.

sb

jump to top Steve_b says:

Fast vehicles with powerful acceleration are necessary sometimes to get around dangerous and/or drunk drivers.

jump to top brennan says:

Jeremiah : My 1985 BMW 318i has an MPG gauge. It's decommissioned and waiting for a budget to be converted to Electric though. :P

jump to top Tim says:

Personal Responsibility!
Soon the government will mandate you go to the bathroom 10 times a day to prevent blader infections.
Stop trying to run everyone's lives.

jump to top Jon says:

I have actually driven at about 100 MPH a couple of times. There are situations and places where it makes sense.

Also, some cars are driven on racetracks.

That said, most cars are not, and I can see no reason any sane person would drive more than about 120 even on the emptiest, straightest road in, say, North Dakota.

I hate outright bans, but I would cap standard equipment speedometers at 100, with speed limiters set at 100 as well. A higher-speed speedo and limiter override should be a legal factory option, but reported to your insurer through a VIN-based listing. The insurer would estimate your risk tolerance accordingly, and of course charge for it.

If you didn't buy an unlimited car and you disable the limiter, you don't merely get fined: you lose your insurance coverage. That's a lot scarier and few people are that reckless.

An outright ban would be politically unsustainable. You might get one, but it would be reversed at some point, as it already was.

Separately, a rate of fuel (or charge) use gauge should be mandatory in all vehicles. Jeremiah is absolutely right. This would pay for itself many times over in both fuel cost and accident prevention/mitigation. It should be completely uncontroversial.

jump to top Alonso Perez says:

If someone "tagged" roads in Google Maps with speed limits, then made GPS units communicate with your speedometer...
then cars were built sensibly...
Wouldn't we all be safer?

jump to top Robert Rowe says:


herman says...
"nyc where speed limits are suggestions rather than law"

Umm.. have you ever been to New York? I've never seen a can go more than 30, how could you?

jump to top Grissom says:

I'm sure one day we will see some high-tech system controlling how fast we can drive, etc. But this idea is a simple one that could actually be VERY effective!

jump to top CoolProducts says:

Personal Responsibility. There it is in a nutshell.

If people wanted to know how fast they could go over 85 mph, they could get a GPS.

My 1982 Cadillac Eldorado had a cool trip computer. Gave you instant mpg, range on fuel remaining, and some other goodies. It was cool to coast downhill and see the mpg go way up.

Nowadays I feel 'unsafe at any speed'. How bout them Avalanches and Escalades going by at 90 mph? Darwin award contestants.

Ah the good old days ...

vsk

jump to top vsk says:

Because some people have small genitalia.

jump to top Anonymous says:

Unfortunately the only thing you have to blame is, how the engineering community sets standards for the use and or settings for gauges.

Gauge (gāj) n. An instrument for measuring or testing.

Now some basic rules on how settings and ranges are done for gauges.
1. Gauges need to read at twice the normal working setting for use.
2. Maximum operating setting needs to be 75 percent of the gauge range.
3. Operating range should be limited to 2/3 of the gauge range.

Now your Speedometer measures speed, GASP!! Surprise, Surprise, a GAUGE.

Now apply some basic numbers to those rules above.
Common speed Engineer's designed cars to running at, 80 mph. Yes, I know speed limits 75 (US). People speed. They know this.

Okay, 80 + 80 = 160.

The max your car, mainly your engine/transmission, is designed to handle before it breaks, 120 mph.

75 percent of 160 = 120

Highest the Engineer's figure people could/should be operating under adverse conditions (when you start to shimmy/ become uncontrollable), about 107.

2/3 of 160 = 106.67

Now as this articles reference 'Tom Vanderbilt' points out a nice Psychological reasoning behind speeding. But Tom, the guys at Stanford University and others, don't the understand the real reason speedometers are the way they are.

“understand how, before you complain about why.”

jump to top Seamus Dubh says:

“understand how, before you complain about why.”

Ok, so now that we know how, I can ask this.

*Why* are the standards set that way?

jump to top Nate says:

Please do not insult "testosterone soaked hard-core engineers this way". There are as many of us on either side of this debate. What your talking about comes directly from the marketing weenies.

jump to top donee says:

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