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.
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 
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.
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.
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!
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.
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.
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.
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.
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
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.
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
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.
The tachometer in a automatic car can help diagnose transmission problems, you can tell if the car is shifting properly or slipping!
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???
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?
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?
Now that’s a good point, Mike A!
My car doesn’t have a tach meter, (1995 Dodge neon, 5spd)
) If you can properly drive a standard, a tach meter is useless.
And I’m totally fine with that, I listen to the car for the most part, (hey, pretty impressive for 16 eh?
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.
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.
Thanks clueless.
It’s useful if you know how to use it. You however clearly don’t know how to use one.
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.
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
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
Well, Andy, I certainly am getting educated about car engines in this thread!