Why Do You Use a Vehicle Tachometer?

The tachometer is a useful automotive indicator

Once only found in high performance and race cars, the tachometer is making its way into more ordinary vehicles, including Mom's minivan. Many driver's are confused about this extra indicator, but it does have some handy uses. The tachometer indicates your engine speed in rpm. Knowing your engine speed can help you be a smoother driver, and get the most out of your vehicle.

Maximize Engine Power

Your engine has an rpm range where it operates at its maximum power. This is usually not publicized with your vehicle information, but you can get a feel for this range, also called the power band, as you drive and feel how well the vehicle moves at different engine speeds. If you monitor this, you can time your shifts so the engine is always operating in the optimum range for the most power output.

Maximize Fuel Economy

You can use the tachometer to help maximize fuel economy. As you operate your vehicle, pay particular attention to the low end of the power band. You want to keep your engine speed as low as possible while producing smooth power. For example, if you notice that your engine produces maximum power between 1,200 rpm and 2,300 rpm, try to arrange your shifting and driving patterns to keep the engine as close to 1,200 rpm as possible at all times. Dropping to low may cause the engine to lug, working it harder and causing higher fuel consumption.

Avoiding Engine Overspeed

Most tachometers indicate a red zone. If you operate the engine with the tachometer in that range for too long, you could damage your engine. When driving a manual transmission and needing maximum acceleration, you may want to shift to a higher gear just as the tachometer approaches the red zone.

Smoother Downshifts

You can use a tachometer to downshift your vehicle more smoothly. As you slow down, push the clutch in to downshift. When you disengage the clutch, keep pushing the brake pedal with your heel, and use the toe of your right foot to increase the engine rpm with the accelerator pedal by about 1,500 rpm. When you complete your downshift and release the clutch, your engine speed will closely match the correct wheel speed, making the shift much smoother. You can improve the smoothness of this procedure as you practice.

Towing

Towing is a high-performance use of your vehicle, and often requires you to drive differently to maximize power and smoothness. Generally, you should operate your vehicle in the higher end of its power band when towing to prevent lugging with the heavier load. The tachometer will help you stay within the power band and give you more control over your vehicle and the load.

Automatic Transmission

A tachometer is used less often in a vehicle with an automatic transmission, but it still has its place. Most modern automatic transmissions are calibrated with electronic shifting patterns designed to maximize fuel economy. But they still can still be downshifted manually, which can allow you a performance advantage when you need it for quick maneuvers on the road, or for towing.

Diagnostic Aid

Particularly with vibration and drivability issues, the technician may need to know exactly when the issue occurs. Using your tachometer, you can tell the technician if the problem occurs at one particular engine speed. This can be useful information as he diagnoses concerns with your vehicle.