Tacky or Techie? The Tachometer.
June 9, 2019
There's a gauge that many vehicles have that says RPM on it. And there are a lot of people who either don't pay any attention to it or don't even know what it is. Here's why it's a good gauge to know about.
It's called a tachometer, and that "RPM" label means it is measuring how many revolutions per minute (RPM) the engine is turning. Automotive experts know that a vehicle's engine can be damaged if it turns too fast (revving too high) or too slowly ("lugging" the engine).
A tachometer (sometimes called a tach) is almost a "must-have" gauge for vehicles with a manual transmission; the driver has to manually change gears; the tach helps the driver know when revolutions are in the optimal range.
Some say you don't need a tachometer if you drive a vehicle with an automatic transmission. It's true that most drivers of automatics don't even look at it. But there are times when paying attention to the tach can help you prevent an expensive repair.
Here's a good example. Manufacturers now build many of their automatic transmission vehicles with shift paddles. They let you shift gears without a clutch. That's manual shifting, and drivers need to know they're not revving the engine too high. That's where the tachometer comes in, since it shows you visually when you are in the red zone (RPM too high).
Here's another way the tach can help you: fuel economy. Generally speaking, the lower the RPM, the better the fuel economy. It's not good to go too low, of course, and the tachometer will help you find that spot of maximum efficiency.
You can also spot problems by paying attention to the tach. When your vehicle stays in first gear longer than usual (higher reading on the tach), then the RPM dip lower than usual after shifting, it may be that your vehicle's transmission is skipping a gear. Plus, if your vehicle's RPM go up but your speed doesn't, it could mean your transmission is slipping. Either situation should be checked by a trained technician.
If your commute takes you down some long grades, you might like to put your vehicle in a lower gear to help slow down the car (and not burn up the brakes). Having a tachometer keeps tabs on when your engine is revving too high.
So, consider the tachometer a "bonus" gauge. It's one more helpful assistant that can help you spot and prevent problems in your vehicle.
More articles from Southside Garage

Stopping "Brake" Downs (Brake Pad Replacement)
April 27, 2025
If someone tells you to put the brakes on something, you know it means stop. And stopping is one of the most important safety maneuvers you can do in any vehicle. That means your brakes have to work properly. Let's face it. You stop dozens of times every time you drive. And over time, that t... More

When Metal Meets Metal (Wheel Bearings)
April 20, 2025
What part of your vehicle has little metal balls inside that are lubricated and allow you to cruise on down the road? They are wheel bearings, and automotive designers might argue they are human beings' second greatest invention of all time (the first is, of course, the wheel!). You have a wheel... More

Such a Little Part (Climate Control Resistor)
April 13, 2025
You expect your heater/air conditioner to work like it should. You have a control for temperature and one for fan speed. You even have a control for what vents the air comes out of. Don't be surprised one day if your blower fan develops a mind of its own and starts going crazy. Most of the ti... More