How Does Your Gas Gauge Really Work?

You must have noticed the inaccurate behavior of your gas gauge, i.e. it’s full and empty for long stretches of time.

The psychology behind why is interesting.

How Does Your Gas Gauge Really Work?

The imprecise nature of the gas gauge is something that has always struck me as odd.

Different auto makers create different tolerances for their gauges, e.g. an old Honda we had stayed on F forever, indicating how frugal it was, my current Jeep starts warning about low fuel with what looks like a quarter tank remaining.

This creates a problem with an unfamiliar gauge, especially when the tank seems to be getting low.

It does seem to be nigh impossible to drive a car completely out of gas, which seems to be a good thing, until you realize that people account for their experiences with the gauges when driving on E, stretching them to the dry point.

I suppose I’d prefer a percent remaining indicator, but that might lead me to madness, e.g. one of my cars has a range calculation for the tank, but its up/down fluctuations make me drive erratically.

Anyway, the gas gauge presents an interesting design challenge. Thoughts?




  1. Fascinating, both because of the technical aspects (the way in which the gas tank capacity is measured) and the psychological ones (the way in which the data is presented).

    But these psychological issues are also found in other measurements. When you look at the SALES of automotive products, how many times does the ad show a base price of $x (excluding taxes, delivery, obscure dealer fees, etc.), but then clarify that the model shown in the ad is NOT the base model? In a similar vein, how many quarterly reports are issued that begin by talking about non-GAAP financials?

  2. Absolutely, the psychology of marketing is equally interesting. As a design example, the gas gauge fascinates me.

    It’s also an interesting case of usage creating its own use cases, a.k.a. learned use cases. If my gas gauge were replaced with an accurate percent remaining number, I would like it better, but I’d probably miss the fuzzy accuracy of the E, i.e. 10% remaining is really 10% remaining vs. fuel light is on, but I can squeeze out a few more miles.

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