How Dashboard Displays Work

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­"Keep your eyes on the road" has been the mantra of every driver's education teacher and nervous passenger, as well as the occasional rock star (The Doors included the advice in their song "Roadhouse Blues"). But the fact of the matter is, we really don't keep our eyes on the road at all times. And that's not to say that we're engaging in dangerous behavior like texting or changing radio stations while driving -- we're actually briefly averting our eyes to aid the driving experience. We refer of course, to the dashboard display.

The term "dashboard" didn't originate with traffic jams that made drivers want to dash their head against something hard in the hopes of losing consciousness, but instead was passed down to us from the horse and buggy days. Fans of the song "Jingle Bells" have long known that the proper speed for a one-horse open sleigh was "dashing," but when horses started to dash along o'er the fields, bells on bobtails weren't the only things ringing. The cries of the driver and passenger likely also rang out as they got splattered with mud, meaning that spirits were definitely not bright, and laughing all the way wasn't an option. So along came a piece of wood that protected the buggy's passengers from all the mud and slush, which was known as the dashboard.


­When cars replaced carriages, that dashboard came too, as an ordinary slab of wood under the windshield. Dashboard displays, or instrument panels, were a little bit longer in coming. If you needed to know how much gas was left in an early car, you put a stick in your gas tank, and if you wanted to know the temperature, you went to the radiator itself [source: Lamm]. By the 1930s, though, cars started coming with gauges, and by the mid-30's, all cars included what has been graciously termed the "idiot light," or a warning light indicating that something is wrong with the vehicle [source: Lamm]. Even in the present day, manufacturers are tinkering with the instrument panel, moving it to the center of the dashboard or packing it full of technology that may make keeping your eyes on the road harder than ever.

So what's taking up that valuable real estate on the dashboard?


Car Dashboard Display

Running on empty.

At minimum, your dashboard display has a speedometer and a fuel gauge. In addition to those gauges, the display will feature some combination of a tachometer, charging system gauge, oil pressure gauge and engine temperature gauge. Let's have a quick dashboard confessional that covers what each part does.

The speedometer, one of the most frequently used tools, tells you how fast you're going. You can read more about this bane of a lead foot driver's existence in How Speedometers Work. Traditionally, this gauge relied upon a cable that connected the speedometer to a gear inside the transmission, but now, electric sensors are used with most dashboard devices. Instrument panels basically have a feed of constantly updated information from around the car; in fact, about one-half of a vehicle's total wiring can be found in the dashboard display [source: Klier, Rubenstein].


Your fuel gauge can make the difference between a happy ending romantic comedy (the fella has enough gas to make it to the church in time to get the girl) or a scary horror movie (couple runs out of gas near an old abandoned warehouse full of werewolves). If you think your fuel gauge is playing mind games with you, you're right. This gauge deliberately stays on full to three-quarters full for a long time to give you the sense that you're getting good mileage [source: Ofria]. And of course, as Cosmo Kramer proved beyond a shadow of a doubt on "Seinfeld," you can keep driving once the needle drops below empty -- though only about 1 gallon or so [source: Buss]. Fuel up on more knowledge about this instrument at How Fuel Gauges Work.

If you drive a stick, you're probably well familiar with the tachometer, which measures revolutions per minute (RPM) in the engine. Knowing this information can help you shift at a time when you'll get maximum fuel economy.

Ever needed a jump when your battery went dead? You might have paid more attention to the charging system gauge or warning light afterwards. The amount of electrical current that the charging system provides to your vehicle's battery is monitored by either a voltmeter, which measures the voltage in the charging system, or an ammeter, which measures amperage leaving the battery. When the battery is using too much of its own juice and depleting itself without getting refilled by the charging system, then these gauges or warning lights should alert you to the problem.

While many of us strive to lower our blood pressure, we should never strive to have low oil pressure. The oil pressure gauge measures oil pressure in pounds per square inch, and you're going to have a big problem if that pressure falls in a car. Unless you want to destroy your vehicle, stop the car as soon as possible when this gauge alerts you to a problem; you'll likely be warned via an oil lamp warning light in the dash. Similarly, if your engine gets too hot, you should also get off the road as soon as you can. Your temperature gauge, which measures the temperature of engine coolant, will alert you to a dangerous situation.

There are a host of other warning lights designed to let you know about the status of the car.­ Though there have been some efforts to standardize these lights in all makes and models, they are currently personalized to some extent by car manufacturers. You might see these lights for everything from a reminder that someone's not wearing a seatbelt to a warning that tire pressure is low. For more details about what a certain light is trying to tell you, consult your car's manual.

­The configuration and arrangement of these instruments varies according to each car. In fact, it may surprise you to learn how much time carmakers spend designing dashboard displays. Read on to find out what makes the cut now, and how that might change in the future.


Dashboard Display Design

Miss the good old days? Here's the dashboard display in an antique car.

First impressions are important, and a dashboard provides your introduction to each automobile you drive. Designers get paid to think about what each person might want from the dashboard, because, unlike with potential partners, you're not likely to ask for a second date with that car if you don't get the information you need upfront. The style, shape and layout of the dashboard can be a deal-breaker when buying a car.

That's why some drivers may have a completely electronic dashboard display, while others still watch the rise and fall of a needle; it seems that young drivers and women, in particular, have more of an affinity for the digital model [source: Barron]. Some drivers want as much information as possible about their driving and their car; people with displays that show real-time fuel economy information might make a game out of trying to improve their driving with each mile. The aging baby boomer generation, however, wants basic information in an easy-to-read format [source: Coughlin].


­The need to control additional technology, from power mirrors to a stereo system, means that dashboard displays will only become more diverse in the future. In 2006, writers at PC Magazine imagined a future dashboard that included drowsiness sensors, advanced navigation systems and voice recognition systems that allow you to ask your car questions. This dashboard of the future will also let you pick which instrument gauges you want to see at a given time and project that display on the windshield, so that less eye movement is required [source: PC Magazine]. That means you'll have more time to move your eyes toward the custom entertainment system, full of your favorite music and videos.

That begs the question, of course, as to when a dashboard display becomes a dashboard distraction. Safety advocacy groups worry that drivers will perceive that most of the driving is being done for them with dashboard gadgets such as self-parking devices, lane-change alerts and cruise control. These people will pay less attention to the road and their driving, while even those who are trying to pay attention will be distracted by the constant hum of beeps and the constant flash of notifications from the dashboard. There's a balance to strike multitasking and keeping those eyes on the road.

Drive on over to the next page for more on the interesting features of your automobile.


Lots More Information

Related HowStuffWorks Articles

  • Barron, James. "Rethinking Design of Car Dashboards." New York Times. March 7, 1985.
  • Bellotti, F., A. DeGloria, A. Poggi, L. Andreone, S. Damiani, P. Knoll. "Designing configurable automotive dashboards on liquid crystal displays." Cognition, Technology and Work. Oct. 12, 2004. (Jan. 5, 2009)
  • Buss, Dale. "Technology Muscles In on the Instrument Panel." (Jan. 5, 2009)
  • Coughlin, Joseph F. "Not Your Father's Auto Industry? Aging, the Automobile, and the Drive for Product Innovation." Generations. Winter 2004/2005.
  • "Dashboard of the Future." PC Magazine. April 25, 2006.
  • "Dashboard-Symbol Plan Sets Off Warning Signals." Washington Post. Dec. 9, 2003.
  • Eisenberg, Anne. "Dashboard Miser Teaches Drivers How to Save Fuel." New York Times. June 7, 2001. (Jan. 5, 2009)
  • Freeman, Sholnn. "Hey, They Moved the Speedometer?" Wall Street Journal. Feb. 13, 2003.
  • Kiley, David and Earle Eldridge. "Car dashboards look more and more like jet cockpits." USA Today. May 30, 2002.
  • Klier, Thomas H. and James M. Rubenstein. "Who Really Made Your Car?" W.E. Upjohn Institute. 2008. (Jan. 5, 2009)
  • Lamm, Michael. "Dashboards: From Dial to Digital." Popular Mechanics. January 1984. (Jan. 5, 2009)
  • Marks, Paul. "Driven to distraction by your own vehicle." New Scientist. Oct. 28-Nov. 3, 2006.
  • McCraw, Jim. "Dashboard Panache: Dials and Gauges and Lights. Oh My!" New York Times. Oct. 20, 1999.
  • Ofria, Charles. "Understanding your dashboard gauges." Family Car. (Jan. 5, 2009)
  • Popa, Bogdan. "How to Read Dashboard Lights." Autoevolution. Feb. 10, 2008. (Jan. 5, 2009)
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  • Wood, Lamont. "Inside the Cockpit of Tomorrow's Car." LiveScience. July 1, 2008. (Jan. 5, 2009)