A reader asked me to comment on a situation he faced regarding calibration frequency for some gages he had on loan from his customer. The gages are only used once a year for this specific customer and—I’m guessing—spend about 80% or more of the year doing nothing.

Before the advent of the consumer GPS, a driver had the instrumentation of the car dash. While useful, it did not provide information about direction, time of travel, or time to destination.