The instrument panel displays a variety of information for the driver's use. Some dashboards contain a plethora of instruments that report aspects of an automobile's performance, and others hold "idiot" lights that light up only to indicate hazards. Perhaps the two most common instruments are the speedometer and the odometer, and the two are really a single device that gets its information from the turning of the wheels. The speedometer tells how fast the vehicle is traveling in miles or kilometers per hour, and the odometer translates the rotations of the wheels into the distance traveled. Odometers show the total mileage logged by the vehicle, and they may also include a trip mileage recorder that can be reset at the beginning of a journey.

A vast number of inventions and improvements color the short history of the automobile, yet its odometer is one of the oldest instruments still...