Tacky or Techie? The Tachometer.
July 2, 2018
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.
Need Service?
More articles from TLC Auto Care

(Timing Belt)
November 30, 2025
You may have heard about an important part of your vehicle's engine called a timing belt, and many know that if that belt breaks, it can cause some very serious engine problems. Not all vehicles have them, and the ones that do generally have smaller engines. The timing belt keeps the engine sy... More

More than Pads and Rotors (Brake Caliper Replacement)
November 23, 2025
You might be familiar with brake pads and rotors, two components of your vehicle's brakes that have to be regularly serviced. Here's another important component of your brakes: the calipers. Calipers are used in disc brakes, the type of brakes now found in most recently manufactured vehicles. A... More

Knowledge is Power (Battery Testing)
November 16, 2025
Its likely happened to you once or twice. You head to your vehicle, open the door, turn the key and lo and behold, your battery is dead. Now youre stranded, may have to get a jump or a tow, and youll definitely be late for wherever you were headed. While your vehicle may sometimes give you warni... More
