Why do speedometers go to 160mph?

TreeHugger asks: Why Do Speedometers Go To 160MPH?

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."

In these times of limited resources and soaring fuel prices (current temporary dip excepted) Having the gauges go this high is promoting irresponsibility. I’m not advocating that the automakers do anything in particular as the first one to drop their numbers would be at a disadvantage. Having numbers this large is just too tempting for some folks and I must say that the ~120 on my first car did get me thinking racy thoughts on more than a few occasions, although common sense did take over before I did something stupid.

One TH commenter Seamus Dubh brings up a very good point:

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.”

He’s right about there being a need for standards but standards to fit specific applications are made all of the time, and what could possibly be more specific than a gauge for measuring automobile speed. Personally with all the craziness I’ve seen people pull on public roadways since gas prices dropped below $2.009 per gallon knowing that the car is capable of certain mechanical feats, and knowing it will cost them next to nothing makes people try some dangerous stuff, like tailgating 2 feet off the back of a Civic Hybrid whether its speeding or going slow enough that a Neanderthal would get the point to back off.

Chuck at CleanMPG also makes a great point:

Ever switched from a vehicle with the tiny analog needle on the speedo to a large digital one? The analog needle is dismissive of the acceleration, while the digital one is in your face. In other words, dashboards have an element of social engineering and can influence the way we drive.

He too is right, I was still just as immature when I owned my Lincoln Continental but because it had a digital gauge I never gave any serious thought to how high the gauge could read.

It seems that the standards governing analog speedometers need to be re-evaluated, now for cars that can actually do 160 that is a topic for another day, but they should have a speedometer that shows their range, plus a bit more for cases where the vehicle is traveling faster than its top speed, like when going down a hill for instance..

What do you think about all of this? Please leave a comment below.

Kacey Green
for the Midlands Hybrid Club
"Promoting the spread of clean personal transportation technologies."k