Tachometer in Mercedes-Benz SLS

A tachometer is another name for a rev counter, the instrument which displays engine speed in revolutions per minute.

The tachometer, sometimes abbreviated to tacho, usually has a red line or area indicating the maximum safe engine speed, and may also be marked with optimum engine operation speeds for performance or economy.

The word tachometer comes from the Greek tachy (fast) and metron (measure).

Not to be confused with tachograph.