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What Is A Tachometer and What Does It Do?

BY: Alex Perrone

car tachometer

Many modern cars have digital speedometers even as they have analog tachometers. For a quick refresher, the tachometer is what tells you which gear your car is on. Every car, whether it has manual or automatic transmission has a tachometer. Even some hybrid or electric cars have tachometers. However it begs the question: why does an automatic vehicle need a tachometer?

Back in the day, the tachometer was absolutely essential for manual transmission vehicles. As a driver saw the speed increase the dial on the tachometer would approach each number corresponding to the next gear necessary to reach a certain speed. Then the driver would time their use of the clutch pedal and up or down shift as necessary to keep driving smoothly.

The tachometer basically assists drivers with shifting as they drive. However, Automatic transmission all but eliminates the need for drivers to have to be fully aware of gears and shifting. Automatic transmission are computerized and designed to do all the clutch and shifting on their own without human interference. The tachometer does not serve the same purpose in an automatic vehicle as it does in manual transmission-equipped cars.

Why Do Automatic Vehicles Have a Tachometer?

To put things simply, there really are no real reasons why a car with automatic transmission needs a tachometer. A driver could go on until their tank goes empty and never ever need to know what their engine speed is or what gear they have been driving on.


Some cars equipped with automatic transmission have modes that simulate manual control over the gears. Even still, the computer in automatic vehicles actively prevents drivers from foolishly over-revving and/or “redlining.” The car’s computer will cut the fuel supply if you try to work against the transmission’s design.

The real reason all cars have a tachometer is cosmetic. Without a tachometer you dashboard could wind up with a big hole or empty space. You could argue automakers could place a clock or compass or map there but that more or less goes against without it, there’d be a big hole in your dashboard.

What Should Be On the Dashboard Besides the Tachometer

More and more cars are now coming equipped with fully customizable video displays instead of the traditional dials and meters. So instead of a gauge You have a high-definition screen, and the computer will creates an image of whatever you need from a  speedometer to a navigation map or even an infotainment display.

car dashboard

There is quite literally nothing to stop automakers from changing things up on the car’s dashboard on a automatic transmission. Nothing is holding them except for safety regulations and their own imaginations.  However an advantage of the tachometer, even in zero-emissions cars is that they alert the driver that the car is indeed up and running and moving.  But in an era of keyless ignition, it remains to be seen if that one simple convenience stays as is.

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