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| Highway Signs |
 Title text: Highway engineers like Planck units because, like the speed of light, the energy capacity of a typical car's gas tank is 1. |
Explanation
In Planck units, speeds are measured in terms of the speed of light, c. 0.000000097c is ~104.6 k/h or 65mph.
The "Next Exit" sign references the Planck Length, which is the (theoretically) smallest possible length, equal to approximately 1.616255 × 10-35 m. 1.39 × 1039 Planck lengths is about 22.5 km, or 14.0 miles. It would likely be impractical for drivers to count the digits in that sign at highway speeds[Citation Needed]. The signs would be better if they provided the numbers in scientific notation for those drivers who understood it, perhaps in addition to the displays as currently shown.
The title text claims that highway engineers like Planck units because the energy capacity of a gas tank is 1. From a certain point of view, cars' gas gauges already commonly use 1 to denote a tank's maximum volume: Empty means 0, then come fractions ¼, ½, and ¾, and then Full means 1. Of course, these numbers correspond to different real volume measurements between different makes of car.
Transcript
[Two highway signs stand along a road with mountains in the background. One wide sign reads "NEXT EXIT" above a number starting with 1,390 followed by around thirty six zeros (some zeros are blocked by post of taller sign). A second, taller sign reads "SPEED LIMIT" above the number 0.000000097.]
[Caption below the panel:] OUR LOCAL HIGHWAY DEPARTMENT IS SWITCHING TO PLANCK UNITS.
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