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Typically one doesn't drive much faster than 80 MPH. Even in an emergency passing situation, it would be extremely rare to drive more than 100 MPH. In fact, as far as I know many cars have governors built into the engines that prevent them from going much faster.

Yet in the United States, most cars made in the last 20 years have speedometers that go up to 120 or 140 MPH. Why? It seems to me like it might encourage people to drive faster. Or does it make the car "seem" faster if normal cruising speed is a smaller percentage of implied max speed?

closed as off-topic by DA01, Code Maverick, Benny Skogberg Mar 7 '15 at 6:31

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    The answer is: marketing (as such, this isn't really a UX question) – DA01 Mar 5 '15 at 16:38
  • Comments are not for extended discussion; this conversation has been moved to chat. – Benny Skogberg Mar 7 '15 at 6:10
  • I'm Closing this question as off-topic because it doesn't ask how users are effected. The question evolves around a possible marketing phenomenon far away from UX. A better question would be to ask how users are effected by a scale where half of the scale never will be reached. Unfortunately, there are already too many answers on this to make that radical edit. Its better to ask a new one, if you're interested in effect on users. – Benny Skogberg Mar 7 '15 at 6:31

12 Answers 12

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Others have focused on the psychological effect of the practice, primarily with relation to sales. But I'd like to focus on what one should think of with a speedometer that is free of these sort of plots.

Different countries different rules

In places like Germany or the Isle of Man, there are highways on which there are no speed limits.

Different countries have different speed laws. Having to tailor each car to its target market would increase cost and distribution complexities.

Rules can change, the system doesn't

To continue the point above, imagine the state of California decides to remove speed limits on some roads - this could cause problems with some cars whose speedometer was designed with some local speed restriction in mind.

Rules are sometimes broken

Imagine your friend got stabbed, he's bleeding heavily, and you must rush him to a hospital. There are no ambulances in your village and the hospital is 10 miles down the highway. It's 3AM and there are virtually no cars on the road.

When the life of someone is at stake, even the most law-obeying citizens might break the speed limit.

Speedometers also communicate limits

While main role is to communicate speed, the speedometer is also representative to the limits of the system, basically telling users "You are this far from what this system can handle".

This is an important point - whatever the normal range of speed is, it is still important for users to know what their car is capable of. In most cases this is important for marketing, but there's also a matter of safety here.

If the limit set by speedometer is a false one, you risk people pushing the car over that limit ("it feels OK, surely the car can handle this"), with no indication when they approach the real limit.

Consider these two speedometers:

A speedometer that goes up to 180 MPH

A speedometer that goes up to 220 MPH

Driving at 160 MPH should be perceived slightly differently on each car.

Now all of the concepts above are surely to be muddled by inconsistencies and marketing plot. But if you exclude the latter, or any other psychological design decisions, it is important to see the speedometer as a system-first type of device.

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    German and other laws are not really relevant for this scale - the speedometers you show cannot be used in any cars sold there, they would need a different speedometer scaled in km/h. I believe that none of the few countries (USA,UK,Canada and a few island-states) that use 'miles per hour' as a measurement have speed limits in excess of 120 mph. – Peteris Mar 5 '15 at 18:31
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    Canada uses km/h – Canadian Luke Mar 5 '15 at 18:45
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    @Peteris The scale on the speedometer is just some ink on a piece plastic, what really matters is the scale at which the hand moves. Maybe car manufacturers do not want to produce two different speedometer designs in which the hand moves at a different scale; they just make one model with two plastic covers, one with km/h and the other with miles/h. – Federico Poloni Mar 5 '15 at 18:50
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    The problem with the "communicate limits" theory is that it's wrong. My current car has a speedometer that tops out at 140 MPH, but I've never managed to get it over about 100. My previous car had one that went up to 110 MPH, but the car itself wouldn't go faster than 65 without a tailwind. – Mark Mar 5 '15 at 20:35
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    "the speedometer is also representative to the limits of the system" - Do you have a source for this? I think this claim is completely made up (and a quote from a Nissan exec in another answer contradicts it). My tiny Hyundai has a speedometer that goes up to 180 mph (290km/h), but it could never go that fast. When I floor it I can barely reach 80. – BlueRaja - Danny Pflughoeft Mar 5 '15 at 22:45
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Doing a Google search for "Why do speedometers go so high?" yields the following top 5 links:

  1. http://ask.metafilter.com/182569/Why-do-speedometers-go-so-high
  2. http://mentalfloss.com/article/59478/why-do-car-speedometers-list-speeds-are-way-over-legal-limit
  3. http://www.nydailynews.com/autos/u-s-speedometers-show-unreachable-speeds-create-nascar-like-illusion-article-1.1275934
  4. http://articles.mcall.com/2010-07-13/opinion/mc-speedometer-explain-it-0714-20100713_1_car-speedometer-mph-salisbury-township
  5. http://www.carmagazine.co.uk/features/opinion/tim-pollard/why-does-your-speedo-go-so-much-faster-than-your-car/

Link 2, from Mental Floss (someplace everyone should be visiting regularly) links to this news video which says why. The article pointing out:

According to former Nissan executive Larry Dominique, “Eighty percent of cars on the road are not designed for and will not go over 110 miles per hour,” regardless of what your speedometer claims. Moreover, tires usually can’t long endure being pushed over 130 miles per hour.

The rationale being pointed out as "There’s a small matter of salesmanship."

Link 3 says much the same thing, but also points out using the same hardware across the world to save money (thus in places, and on models, where over 85 is possible):

The answer has deep roots in an American culture that loves the rush of driving fast. The automakers' marketing departments are happy to give people the illusion that their family car can travel at speeds rivaling a NASCAR racer. And companies often use one speedometer type in various models across the world, saving them money.

It goes on to call out a few examples...

In China and Europe, governments require that the top number on speedometers be higher than a car's top speed. Cars sold in Europe, for instance, have faster top speeds than those sold elsewhere because they can be driven over 150 mph on sections of Germany's Autobahn. So to sell the same car or speedometer globally, the numbers have to be higher, said Kurt Tesnow, who's in charge of speedometer and instrument clusters for General Motors.

Link 5 goes on to talk about some of the greatest offenders on the matter:

Mini Countryman 30% of dial unused

Audi A1 26% of dial unused

Skoda Superb 26% of dial unused

Seat Alhambra 25% of dial unused

VW Touareg 25% of dial unused

BMW M5 23% of dial unused

Audi RS3 23% of dial unused

Jaguar XF 22% of dial unused

Kia Optima 22% of dial unused

Audi A1 21% of dial unused

Ford C-Max 17% of dial unused

BMW 1-series M Coupe 14% of dial unused

Infiniti M35h hybrid 14% of dial unused

Saab 9-5 11% of dial unused

Mercedes CLS 6% of dial unused

Honda CR-Z 0% of dial unused (NB digital read-out)

TL;DR: A quick Google search indicates the primary factors are (1) marketing and (2) cost savings.

  • Comments are not for extended discussion; this conversation has been moved to chat. – Benny Skogberg Mar 6 '15 at 5:43
  • Just saying I own a BMW M5 and it uses 85% of the dial while limited (170/200) and the entire dial when the limiter has been removed (203/200). – Carl Feb 17 '17 at 9:36
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Speedometers are an good example of UX hierarchy of needs

The aspirational speed markings (e.g. above 130mph) are functionally useless for many cars, but they enhance the driver's experience by providing the illusion of performance for drivers who have spent tens or even hundreds of thousands of dollars on their car.

Aspirational markers may be functionally less clear (more dense text), less accurate, and less safe, but as long as they meet a reasonable standard of safety and performance, it makes sense for UX to aim for better driving experience rather than driving function.

For the same reason, mechanical watches are less accurate, heavier, and more brittle than digital alternatives but despite being less functional, they provide a better ownership experience for many consumers who are paying a premium not for timekeeping functionality, but for experiential satisfaction.

  • I like this answer but in terms of UX, this is almost black-hat patterns we're talking about. – DA01 Mar 7 '15 at 3:56
  • @DA01 yup. I'm fascinated these approaches though, because they represent an attunement of UX towards more holistic user needs. It seems to continue the trend of reaching further into behavioral psychology and economics to design immersive user experiences. All your UX base are belong to us. – tohster Mar 7 '15 at 4:10
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    yes. Though I do worry about crossing over to the dark side (ie, marketing. :) – DA01 Mar 7 '15 at 4:20
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Actually, the US is one of the few places to have enforced a limit on the maximum speed shown on a speedometer (reportedly to stop people trying to "speed test" their vehicles). For vehicles produced from 1979 to 1981, you'd only see vehicles showing up to 85mph:

enter image description here *The same law dictated the highlight at 55mph http://en.wikipedia.org/wiki/National_Maximum_Speed_Law#Speedometers

As others have mentioned, some countries require a speedo to show the maximum speed a vehicle is capable of (or have no / much higher speed limits), in other cases the manufacturer chooses to (possibly for marketing purposes) display higher values. For example, check out the speedo from a Suzuki Hayabusa:

enter image description here

Then we have a typical BMW car speedo, where most of their vehicles are limited to 155mph, the speedometers generally read up to 160mph (even on the models that don't produce enough power to ever achieve that speed):

Hayabusa Speedo

From a UX perspective, it's probably better to provide a display (a gauge in this case) capable of showing all the possible values.

The use case for this in terms of speed could be:

  • Differing local restrictions (driving to other states or different countries).
  • Use off the public highway (track days, testing, racing).
  • Changes to vehicle parameters (more power, improved aerodynamics) either during production or after market.

The downside (of a gauge) is that the wider the range you attempt to cater for, the less readable it is and it becomes more difficult to determine your exact speed (as the needle is raised, perspective can affect "read" speed).

Digital displays make it more difficult to read changing values / assess rate of change, but you only need to consider the appropriate number of digits (tens, hundreds, thousands etc.) - a three digit display should cater for most cars, though owners of vehicles incapable of 100mph/kmh might question why their speedos go so high too. :D

  • Welcome to StackExchange UX! The points you raise have already been made in previous answers so I am not sure that this adds to the discussion. – tohster Mar 6 '15 at 16:46
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    @tohster I didn't see anyone mention the fact that the US used to have an 85mph limit on speedometers - I thought that would be relevant in discussing why they don't anymore? – Michael Mar 6 '15 at 16:49
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    I think the historical 85mph speed limit isn't relevant to the question, since it specifically asks about speedometers in the last 20 years and you are referring to a limit that existed in 1979-1981 – tohster Mar 6 '15 at 16:52
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    The 85mph is a real problem for exported vehicles, and pegging the speedo = uncertainty. The US is pretty unique in that one does not drive across borders that often or on fast roads. Generally the braking systems have to cope with an emergency stop from terminal velocity, so going off the dial is an apparent indication that design parameters are being exceeded. Valve float/bounce and upper cylinder wear are enough of a deterrent for me. But you cannot assume the vehicle will not be used "as a vehicle" and may travel elsewhere. GPS systems are widely used now as well. – mckenzm Mar 6 '15 at 21:59
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Interesting question. Looking around online, it seems to be a combination of marketing (makes the consumer think the engine is powerful) and manufacturing efficiency (can use the same speedometer in faster cars as well as minivans).

http://mentalfloss.com/article/59478/why-do-car-speedometers-list-speeds-are-way-over-legal-limit

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It's often set so 65mph / 110km/h (which is a common speed travelled on the highway in north america, legal or otherwise) is on top. It makes it easier to glance down and see your speed on the highway.

If it's pointing up, everything's good.

  • But that only works on the highway (when you presumably have lots of time to look at the gauge), in city driving when you need to concentrate more on the road, you may only see the gauge from your peripheral vision which is when having a simple geometrical position to remember would be more help. If the scale topped out at 85mph, wouldn't it be just as easy to remember that when the needle is horizontal then everything's good? – Johnny Mar 5 '15 at 18:22
  • But you're travelling at a higher speed, and travel more distance in that quick second. It's the most consistent reasoning I've found across all sizes of speedometer – evandentremont Mar 5 '15 at 18:26
  • That is an artifact of the fact that most cars have speedometers that go from 0 to 120 or 140, so 65mph is on topish (because it's about half way). If you look at any "sporty" car, they usually go to between 160mph or 180mph (and some even up to 200mph), so 65mph is only about 1/3 of the way up. – Nick2253 Mar 6 '15 at 0:24
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    (+1) That's an interesting idea, seems to make sense. The answer would be better if there was some evidence for it, though. – Gala Mar 6 '15 at 5:49
  • I think this answer could become more understandable if it were enhanced with an explanation why/where 65mph or 110km/h are a desirable speed on a highway. – O. R. Mapper Mar 6 '15 at 13:56
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It is the same here in Europe. I think it is for 3 reasons:

  • Industry costs: It would be too expensive to make different speedometers models for each car based on their max speed
  • Precision: Depending on the speed, speedometers can be quite unprecise (+/- 5 km/h). Increase the scale allows to hide that fact.
  • Marketing: Have the same speedometer scale for a Porsche or a Renault does not allows the customer to simply estimate the performances of the car based on the speedometer.

I have absolutely no proof of what I say, but I spent some time in the car market and this is the explanations I see.

  • If you read my answer, I think it serves a very good argument why speedometers should be based on max speed. There's an important safety issue involved here. – Izhaki Mar 5 '15 at 17:36
  • @Izhaki Since others have shown that they are not, it's kind of moot. – Gala Mar 6 '15 at 5:58
  • speedometers in most jurisdiction must indicate between the true speed and speed+10% + 4kmh (EU regulation) that's 15kmh margin at 120kmh – ratchet freak Mar 6 '15 at 14:42
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I imagine there's some parts commonality going on. My Toyota has a 140 mph speedo which is shared among a number of models. Mine is a sports car that I take to the track and have hit 125 mph in. Track users kind of need the speedo to go that high, other people don't, but there's no extra cost in setting the speedo higher and being able to use one across family and performance models. So, it can make everyone happy without increasing costs.

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    To be fair, track cars don't care about the speedo either. What track has a speed limit? Everything else should be based on RPM. – Bryan Boettcher Mar 6 '15 at 19:39
  • Sure they do! When at a casual track days (without timing equipment), the speed at braking points is used to gauge the effectiveness of the chosen line. – Brian Knoblauch Mar 7 '15 at 20:46
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The UX aspect of this is that by squishing all the important detail into a smaller part of the dial it makes it harder to read and less sensitive to minor variations in speed - particularly if the speedo is trying to show both kms and miles.

And it begs the UX question as to why the analogue speedometer doesn't seem to have been replaced with the digital one on most cars...

  • Some speedos are not linearly scaled, allowing accuracy at slower speeds. Digital readouts are harder (thus slower) to read. Analogue makes sense in situations where you don't have excess time – Carl Feb 17 '17 at 9:45
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I think it's far more mysterious why some people would think that a speedometer would omit showing speeds above typical speed limits.

The jurisdiction of laws is limited to specific roads. There are places where one can drive at higher speeds than highways, such as private race tracks.

Also, if your speedometer was so in awe of typical speed limit laws that it stopped at the legal limit, how would you even know if you were exceeding the limit, and by how much?

  • This isn't about speed limits, it's about driving speed. – shadowtalker Mar 6 '15 at 1:15
  • Questions is why do they go so high over the limit, nobody is arguing it should stop exactly at the maximum allowed speed in a specific jurisdiction. – Gala Mar 6 '15 at 5:59
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Zhaki nailed it. In addition, there is some benefit in a gauge of placing the most common reading in the middle of its range rather than close to the high end. Many measuring devices exhibit different systemic errors in the mid range than they do at the top end. Old fashioned voltmeters and multimeters behaved this way. you could get a slightly more reliable reading by choosing a scale that was roughly double what you expected to measure.

If this is the pattern, then a speedometer that most often going to be checked at 65mph might be calibrated so that the top end is 130mph. In my car, that's about how it is. Moreover, 65mph is just about vertical ( the gauge is analog). So I get an intuitive grasp of my speed without even reading the numbers. This makes a real difference in terms of how long my eyes are off the road.

But it's probably mostly marketing, and mostly deceptive marketing at that.

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    I would argue that, unless you actually live outside of civilization, the most common reading is somewhere between 20 and 40 mph. – O. R. Mapper Mar 6 '15 at 13:58
  • @O.R.Mapper but I don't think people actually check their driving speed as often on those roads ace it probably varies a lot more anyway. Stopping, turning, cars in front of you doing the same – shadowtalker Mar 6 '15 at 14:03
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    If close to the interstate means outside of civilization, then I guess that's where I live. – Walter Mitty Mar 6 '15 at 14:06
  • @ssdecontrol: Maybe that's different in the U.S., but in my country, automated speed controls are especially done within cities, to enforce restrictions to 30/40/50 km/h. Drivers here will regularly want to check their speed to ensure they're maxing out what is allowed without exceeding the speed limit, essentially after every corner or junction where they may have temporarily slowed down. – O. R. Mapper Mar 6 '15 at 14:10
  • I don't think this answer is correct. Other gauges on the dashboard (e.g. RPM, fuel) are certainly not calibrated this way so that would be some pretty bad UX consistency, and anyone who has piloted a plane (where gauges matter a LOT) will tell you that needles are certainly not calibrated this way. – tohster Mar 6 '15 at 16:49
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To put it simply: people DO go that fast in conventional cars - when they take them to the race track.

There are plently of open public race tracks in the United States, and they don't all require you to take or own a race car in order to drive them. In fact, there's plenty of races that pit completely unmodofied commercial cars against each other.

Not to mention commercial cars are tested for top speed, and why bother changing the speedometer out after testing, when the test speedometers will do just fine?

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