The tachometer – the most useless car component…

Modern car dashboards have numerous indicators and controls. Some are necessary: without a fuel gauge, for instance, we’d be in frequent trouble. Others are optional but quite useful: the rear collision warning beeper is a good recent arrival. But one indicator is totally unnecessary, yet present in a great many car models: the Tachometer, or engine RPM indicator.

Car Tachometer and Speedometer

This meter is very impressive, to be sure, and on a race car would be quite useful to help the driver wring the ultimate performance without destroying the engine. But this meter, at left in the photo, is not from a Formula 1 car; it’s from my faithful but mundane Mazda 3, with which I navigate the congested roads daily to get to work. You think I constantly glance at the tachometer to set the gears so my engine’s not redlining, when I’m stuck in traffic jams half the time? Even if I were so inclined, this car has an automatic transmission!

Fact is, nobody uses this indicator on a family car; yet the manufacturers put them in – adding just a little bit extra to the waste of energy and resources needed to produce the car. I suspect this is another of the cases where fashion, vanity and marketing get together to override commonsense design – we get this meter because it looks flashy, fashionable, macho… hey, I have an RPM gauge like the race track pros!

Millions made – none needed :-(

    34 Responses to “The tachometer – the most useless car component…”


    1. 1 Josh Bancroft

      Tachometers are close to useless on automatic transmission cars, but they do serve on purpose – to let you know, visually, what gear you’re in. That is, on my automatic transmission car, I can glance at the tach, and know which gear I’m in, depending on my speed. There’s no other way to know.

      And on a manual transmission, a tach is much more useful, for deciding if you should shift gears (granted, it’s not hugely important in normal driving, and you could get along without one). I’m the kind of person who likes to know what my car is doing in every way – the kind of person who wants to know what my CPU and RAM utilization are at any given moment on my computer, as clues to what it’s doing, and if it’s working normally.

      Besides, it’s probably harder and more costly for car makers to make completely different dashboard instrument panels for different versions of their cars – one with a tach for manual transmissions, and one without for automatics. It’s easier and cheaper just to include it, for the people who care, and for the people that don’t, well, they get to be irked by how wasteful and needlessly complex they are. ;-)

    2. 2 Asa

      Actually, I do use the tachometer.
      In my motorcycle, for instance, the speedometer is significantly less important – I am much more interested in the RPM than in my speed.
      Same goes for my wife’s car. But there is a difference from your case – we have (and prefer) manual transmission. I want to shift the gear whenever I want to, not whenever the machine ‘thinks’ it should. And the best way to know when to shift is the tachometer.
      I agree that the tachometer isn’t needed for automatic transmission. But in my opinion, so is the driver – If I wanted somebody else to shift the transmission, I’d probably want somebody else to steer the wheel. It’s called a Taxi Driver.

    3. 3 Nathan Zeldes

      Ahhh… some controversy! :-)

      Of course, you’re right, Josh and Asa… in a manual car it makes more sense, and those with a passion for cars (and, even more, motorcycles!) would indeed make use of this dial. Though IIRC, didn’t one use one’s ear to keep track of the right moment to shift? I do miss the manual shift, but with traffic jams being so common, the benefits kinda paled…

      Incidentally, on my automatic you still don’t need the tachometer to tell what gear you’re in – Mazda used a belt-and-suspenders approach and threw in a digital readout of the current gear as well. No amount of complexity is too good for our customers!

    4. 4 charlie

      actually, when i race my corvette on the track, the tach is used and the speedo is never used. most special purpose race cars i’ve ever seen do not have a speedo. around town, i use the tach to control gas mileage.

      i also race in something called auto-cross, which uses stock and normal daily driver cars as track cars, and i don’t think tachs are useless there either. it would be hard to make them optional on normal cars, and the manufacturer can’t know what the end use is going to be.

    5. 5 Igor

      Tacho is most usefull thing on a dashboard in manual shift vehicle, even in everyday trafic. I would rather sacrifice fuel consumption gauge, which is quite useless anyway, than a Tacho. Altough in your average MPV you could put a smaller version, it does not have to be that big and take up big part of dashboard.

    6. 6 Rob

      Another critical use for a tach is if the car is ever stuck. If the wheels are pulling without resistance (ice/mud) you need to be careful not to over-rev the engine when trying to get out.

    7. 7 abalastow compendium

      The Tach is also useful for diagnosis. I can tell some thing about my engine by the RPM it idles at or I can tell if the AC compressor has just kicked in, or if it’s about to stall. It is useful when shifting as many modern cars have very good sound insulation. I can tell when my tires have broken loose in the snow. It is necessary to prevent over-revving while engine braking. Also, some of use drive spiritedly everyday.

    8. 8 kipp taylor

      I stumbled across this letter looking for more tach information. I have
      an automatic now and I ordered a tach today. I don’t hear as well as some people and I need the tach to tell me what the wheels are doing on ice &snow and to tell me if the transmission is slipping before it gets bad and costly to repair. The people who make cars have a little more on the ball that the author of tachs are wasted space. Kipp

    9. 9 justin

      The tach is wuite useful for cruize control.

      There have been many times I will set the cruize control based on the tach in order to save fuel.

      It’s nice to know when dropping 3mph puts you a gear higher and saves almost 10% fuel efficiency.

    10. 10 Rob H

      I don’t think the fuel gage is that useful. I don’t even have one on my motorcycle….A low fuel light is enough, really.

      The tach is as important as the speedo IMHO, especially in a manual shift car.

      Actually my wife’s 2000 neon doesn’t have a tach, but we use a an obd2 reader to get the engine speed :)

    11. 11 Havnar

      If there is 1 thing that’s usefull in a car, it would be the tachometer!

      People saying it isn’t are in fact themselves not usefull in (or in fact near) a car.

    12. 12 jdawg

      The tachometer in a automatic car can help diagnose transmission problems, you can tell if the car is shifting properly or slipping!

    13. 13 paul

      You all forgot about tuning a car. This only
      applys to older cars, but a tach is needed to tune the engine.
      You set idle mixture screws, reset the idle speed using
      tach then adjust timing and re-ck rpm.Also on some
      older cars you can over rev the engine and blow it up thats
      why they come with one set dial for your redline, this is after market
      of course. you see rev your car real high and keep it up there all the oil will leave the pan and it will heat up and cause major damage
      most people dont rev the engine like i do but I need a tach to go fast.
      and stay tuned!!!!!!!!!! all the rest is crap, most drag race cars are automatics any way think they use a tach???

    14. 14 Mike Regan

      I guess none of you know enough about how to use a tach, nor know when it would be nice to have it’s features to use..BTW, not all cars come with tachs. Most are on specially optioned cars, or ordered with one. A few cars have them as standard equipment.
      Maybe you should learn more about it. When it’s handy to have.
      I would not want a car that did not have one.Especially in the winter when one can get stuck in mud or snow.
      But I guess you’re too wussy to drive in it huh?

    15. 15 Mike A

      So the argument is that adding a tachometer takes extra resources, yet I think everyone here agrees that tachs are almost necessary for a manual transmission car. Thus, for a given model (say, a Mazda 3, which has a large enthusiast following), at least some of them will need a tach. So which uses more resources, the act of putting a tachometer in a dash, or having to retool for having two completely separate dash styles for each car?

    16. 16 Nathan Zeldes

      Now that’s a good point, Mike A!

    17. 17 Kristian

      My car doesn’t have a tach meter, (1995 Dodge neon, 5spd)
      And I’m totally fine with that, I listen to the car for the most part, (hey, pretty impressive for 16 eh? :) ) If you can properly drive a standard, a tach meter is useless.

    18. 18 gg

      I use the tach in my manual transmission car to keep rpms to the min – gets me better mileage. The tacho let’s me stay in a rev band of 2000-2500, optimum for my engine – can keep away from redline by ear, but can’t target a low / narrow band.

    19. 19 Brad Ocock

      You honestly complained about a tach adding “that little bit extra to the waste of energy and resources to build my car”?

      You do know, of course, that an automatic transmission-equipped vehicle gets worse fuel economy than a manual transmission, right? While cruising at 70mph, an automatic trans will run the engine several hundred RPM higher than a manual trans… something that useless tach would indicate.
      An auto trans also has many more moving parts, which cause parasitic drag through the driveline, also affecting fuel economy.
      They’re also heavier than their manual counterparts, requiring more gas to haul down the road.
      But let’s talk about “wasted energy to produce.” Lots more pieces in an auto trans, and a lot more machining with big, mean 3-phase industrial machines that suck down so much more power than it takes to build a tach.
      Oh, an auto trans also requires a bigger radiator than a manual–more aluminum. Sometimes they even have their OWN cooling radiator. They certainly require a bigger cooling fan, which uses more electricity, which requires a bigger alternator.
      And it is filled with several more quarts of that nasty old petroleum than a manual trans.

      So stop being an idiot and acting holier-than-thou about a tach wasting energy to build, while you’re wasting far more energy because you’re too lazy to shift your own gears, or too incompetent to do it.

    20. 20 I use a tach

      Thanks clueless.

      It’s useful if you know how to use it. You however clearly don’t know how to use one.

    21. 21 Nathan Zeldes

      Hey Brad, thanks for the detailed analysis. No question that a manual shift is more economical – and in it a tachometer would in fact benefit a savvy driver to increase that economy further. my gripe wasn’t on environmental grounds, it was on lack of utility grounds (in an automatic car).

      Personally I love driving with a stick shift when I get the occasion, but with the endless stop-and-go of our traffic jammed roads I find the automatic has its benefits too.

    22. 22 ProjectD

      Good day fellow posters: I recently went to a used car parts shop to inquire about purchasing a Corolla engine: It was either the 5E or 4E. When I looked at the engine a second time I realised that the the engine that the dealer was telling me was a better one had a smaller alternator to me having a bigger alternator meant a bigger engine or more powerful. So I was questioning the guys “if they were making a mistake” by suggesting the 5E instead of the 4E.

      I was making a mistake between the Corolla 4A and 5A engines. The Corolla older models carry a 4A engine which is a 1.6 engine, and the 5A is a 1.5. So I thought the same thing applied to the newer models engines. This was not true…. on the flip side the 5E is the bigger engine and the 4E is the 1.5 engine.

      So I started doing some research and I came across this little discourse. “Weather the RPM was needed yes or no?”

      The person who started this discourse need to get a little education as I did on some factors of a car and it’s components.

      1. Any car that does not have a RPM gauge is making no sense. For tuning purposes both manual and transmission cars, a RPM gauge is needed.
      (a) If the car is idling to high or to low: a/c, gas, cab.adjustment etc.

      2. If your transmission is sticking or the RPM is to high when changing gears on the highways/roads etc. It tells you as the driver that something could be wrong with you transmission or engine.

      3. As for you guys in snowy countries… you know the drill, and as one of the noted use above, a person who cant hear well he knows when to change a gear when driving. I think that’s a much bigger reason.

      Nathan my friend, before you start pointing out usefulness or not on car parts and components, read over all others have said on this matter, and some things may not be useful to you, but it may have great need and value to someone else.

      Andy G. Hypolite
      TAXI DRIVER/PHOTOGRAPHER/ARTIST/CAR LOVER
      TRINIDAD & TOBAGO

    23. 23 PROJECT"D"

      P.S.
      …and before I forget, the bigger alternator which was on the smaller engine, 4E, was there because the transmission engine needs ore electrical power to run the cars transmission and components,and it is the smaller engine!

      Andy G. Hypolite

    24. 24 Nathan Zeldes

      Well, Andy, I certainly am getting educated about car engines in this thread! :-)

    25. 25 dave

      a tach can be useful even in an automatic car, like for instance if your idle starts to fluctuate you know know something is off or if your rpm drops to low or idles to high, even on an automatic car that gaves the driver a idea that there is an issue in your car in an automatic or manual cause not all issues can trigger a CEL (check Engine light), so a tach can be useful on both automatic and manual cars

    26. 26 Rosie

      Even with my limited knowledge and automatic transmission, I think it is useful…

    27. 27 vapacker

      Most men whose vehicle have an automatic tranny never use the tachometer. Most women have no clue what a tach does. They do know it looks cute next to the speedo thingee. Probably no single accessory has wasted as much money as tachs in USA cars with automatic transmissions. The hundreds of millions of dollars wasted on tachs over the past 50 years should have been used on safety devices or bach-up cameras instead.

    28. 28 davet

      I really have a hard time believing that everytime you want to shift
      your manual transmission car you look down at your tach. think about it…

    29. 29 Arshxd

      The reason that they put it in anyway is probably because the tach itself on a modern car uses the timings put out by the ECU, so there’s actually the cost of the tach consists of what you see on the dash, namely the needle and the dial. And as many have stated above, while it a tachometer is useless in an automatic, it is useful in a manual. But the cost of having separate indicators for both transmission types far outweighs the cost of putting the a tach on both. A case in point is the Toyota Vios of Asian markets. It doesn’t have a tach on auto models, BUT neither does the manuals.

    30. 30 Sid

      I live in India and about 95% cars in India are MT. I have driven AT few times, however I prefer MT over AT as it gives me more control over power and speed. I look at RPM meter all the time and is very useful piece of instrument. I cannot even think of buying a car which does not have a RPM meter! I drive a lot and go places and RPM meter is a must if you are ascending or descending a hilly area.

    31. 31 Aitch RPM Puzzled

      Ref Sid’s reference to RPM meter being a must if ascending or descending a hilly area. How does this affect the RPM and how should I respond, especially if going downhill? I assume I would change down if going uphill, but should I not do the same if going downhill? I would on a pushbike, for safety’s sake!

    32. 32 Richard

      I’ve had my Lincoln Aviator . It has a giant RPM dial that frankly has practically never moved, ever, in over 10 years. It is a total waste of space, money etc.

    33. 33 Willy-bill

      I recently picked up an 86 F150, with a 3-speed automatic. I suspected the transmission was slipping at around 15 to 25 Miles an hour (normal for the C4 and C6 tranny’s of that time period). Since I was intending to do so anyways, it just made my reasoning for installing a tachometer more sound.

      Long story short, if a vehicle didn’t come with one stock, irrespective of whether it featured an automatic or manual transmission, I put my own tachometer in. I’ll be adding an engine oil temp guage, as well as a transmission fluid temp guage to the mix. Anyone who thinks these guages (and most of my friends do) don’t care to take preventitive care of their vehicles.

    34. 34 InlinePaul

      Tach is not needed in manual or automatic vehicles. We drove for years without a tachometer, manual and automatics. Never had a problem. I covered the tach in my manual transmission vehicle because it was annoying and now driving the stick is much nicer without it because instead of glancing at the tach I can simply pay attention to driving and shift better too.

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