Tachometer (Rev Counter)

It helps choose the right gear. The red zone marks the maximum speed. Some electric cars show power instead. Gear shift indicators on the instrument cluster suggest when to shift for economy. Some sports cars have shift lights that flash near the limit. A needle that jumps or drops to zero while the engine runs smoothly usually means a signal or display fault rather than an engine problem.

The display receives the speed signal from the engine control unit.

Erratic readings can indicate sensor problems. Shift up early to save fuel.