On September 1st, 1979, the National Highway Safety Adminsitration added a provision for a maximum speed reading of 85 mph into a regulation focusing on speedometer accuracy. The law itself only lasted a few years, but the 85 mph speedometer endured solidly throughout much of the 1980's.
The intention of the mandate was to restrict top speed and a driver's impression of how fast they were going, in an effort to increase safety and fuel economy. A needle at the top range of the speedometer indicates the vehicle may be approaching its limits, psychologically. But from a practical standpoint, 85 mph was a good maximum for safe speed in any vehicle.
The 85 mph speedometer did not endure because people didn't want it, not for any reason of practicality or usefulness. Drivers want to believe that their car can go like a race car, if necessary. In reality it just isn't true. Not only are most fuel cutoffs and electronic governors set well below most speedometer limits today, the vehicles are not geared to physically drive as fast as a 160 mph speedometer might pretend to allow.
Some drivers argue that they want a bigger speedometer in case they want to race their car. In reality, most drivers do that as often as owners of large SUV's take their vehicles offroad. Even if the vehicle can physically do it, most drivers never will.
A speedometer with a lower top speed can be read more accurately. A wider spread of numbers means the distance between numbers is greater, making the needle sweep slower, and over a wider area, thus easier to read.
It also looks better and is more practical in our opinion. Why have a gage with 180 mph that will only ever be half used? It would be like having a tachometer that goes up to 30,000 RPM, or an oil pressure gage that goes up to 500 PSI. There just isnt any practical point for 99% of drivers. The speedometers in the picture below have needles that barely even move to reach 45 mph, which is a very common speed. Even below that is harder to read accurately.
If the vehicle is made to go that fast regularly, then sure it makes sense. But for almost all cars and especially trucks it makes absolutely zero sense. Besides most speedometer upper regions being grossly illegal just about everywhere, such speeds are also horribly unsafe. A standard 85 mph speedometer is much easier to read, especially at lower speeds which are more commonly driven.
So why make unattainable speeds the norm for all speedometers? Psychology. Drivers want to believe they can go fast; that they possess the skill and capability of high speed. Rediculous speedometers exist and are mainstream because most people who decide car options and layouts are idiots. Whether its the designers who think its a good idea, or marketers who use focus groups, or executives who want to sell more flashy things.
In reality it is just a lack of common sense, perspective, and pragmatism. Which in our opinion makes driving a little less fun. Because after all as the saying goes 'it is more fun to drive a slow car fast, than a fast car'. So why not make the car 'feel' slower than it really is by putting in a realistic speedometer?
Or better yet, with the advent of programmable, configurable digital dashboards, why not make the speedometer range customizable as well? That would be the ultimate solution.
Why haven't vehicle manufacturers made dashboards more customizable? The capability exists. But the manfacturers prefer to make things like different colors available rather than anything truly practical. Why not make gage position, range, and function customizable as well?
The early digitzed numeric gages were a start. Since it was just a reference number with no perceived upper or lower limit, the limit arguments are compeltely nullified. Some even had different functions or adjustments. But those soon went out of style.
Vehicle manufacturers seem to be under the illusion that drivers are too stupid or lazy to even WANT to truly customize their gages, other than a few little useless tweaks. We believe that many drivers would love this feature.
If the dashboard is basically a screen anyhow, it is not that hard to make different options available. If not a few preset, pre-programmed configurations at the least. Best case would be a gage cluster that could be rearranged and reconfigured with a phone app or computer.
Vehicle manufacturers seem to want to tie electronic devices such as phones into our vehicles, but they don't really seem to know what to do with the technology. Configurable dashboard technology would be the perfect use for this connectivity.
Just like any other configurations, if the driver does not want to go to the time to configure their settings, then a default configuration can function perfectly well. But for those who desire the capability, it would be a wonderful integrated use of technology.
A configurable digital gage cluster with a core default setting would be the best solution and make all drivers happy.