Est. 1998 — 27 years of woodworking knowledge
O.T. Pickup and Auto Dash Boards
Stuart Johnson
With automatic transmissions and normal driving why are tachometers in all the dash boards. I thought the purpose was to see how high the rpm was for manual shifting when racing. Just one of those little things that pop into my mind when driving bored.
Re: O.T. Pickup and Auto Dash Boards
Bill Houghton, Sebastopol, CA
Probably mainly entertainment value, although I think there's still a residual sense that a tachometer is a sign of a higher-value car.
Many modern automatic transmissions have a manual shifting option. In theory, a tachometer would have value then - you can tell when you're getting close to redline (maximum safe engine speed, although modern tachometers don't seem to have a visible redline) - but a lot of those transmissions will shift up for you if you don't shift when you hit redline.
The newer of our two cars turns the engine off at stoplights and in stop-and-go traffic, and I notice the tach go to zero then, which is mildly helpful.
And I have to shift our RV manually in the mountains fairly often, because, for some reason, it doesn't like to shift into the lower gears by itself; so I find the tach useful in that vehicle. When I'm in first gear, as I was going up 10,000 feet, on the twisty road to the bristlecone pines in the White Mountains of California, it's nice to know when I need to back off a little to keep the engine at a safe rpm.
But I get irritated when I drive a car that has a tach, but no water temperature gauge. THAT is a helpful gauge, even if only rarely in the modern car - but, when the temps go higher than they should, it's a good signal that there's trouble under the hood.
More useful guages
Tom Dunlap
A vacuum gauge is much more useful than a tach. Keeping a high vacuum reading will give better mpg. There are other things that a driver can find too
Engine water temp!
Oil pressure
Automatic transmission fluid temp gauge. Especially if towing and going up lots of hills.
Re: More useful guages
Bill Howatt
Useful for whom? Sure if your a bit of a motorhead knowing these things is nice but for 99% of the population having an idiot light come on with a chime is more of an attention-getter and more likely to be investigated. Ask most people what it means if the oil pressure drops by 15 PSI and see what answers you get.
However, I do think a coolant temperature gauge should be present with an idiot light. My 2017 Caravan has a gauge.
Tachometer? Just there to balance the large dial of the speedometer, IMO. I can manually shift the Caravan's auto up and down easily but it isn't a real useful feature either. Trailer towing might make it more useful.
Bill
Re: O.T. Pickup and Auto Dash Boards
John in NM
The tach is useful for helping to keep fuel consumption down to the minimum, but Tom is probably right that a vacuum gauge might do that a bit better.
Funny thing is that they used to be less common - I never had one in a vehicle until the 1990's. Driving that car a lot is how the mpg vs rpm relation really clicked - no one taught me that, it just became very obvious with a tach. So if I were buying a car for a teen I would make sure it had a tach and then make him pay for the gas! 
Re: O.T. Pickup and Auto Dash Boards
John McGaw
My 2018 Subaru Outback has an indicator for, among other things, an instantaneous display of fuel consumption as well as the average since the last fill-up and I find that more practical than a vacuum gauge. My 2008 had these also. I agree that, in normal driving, the tachometer is not the most useful thing conceivable but at least the Subie does have a real temperature gauge. It has a dazzling number of "idiot light" indicators, more than most drivers will ever remember and these forced me to actually read a car's manual in detail and more than once to figure everything out.
Re: O.T. Pickup and Auto Dash Boards
Ray Mtn. Home Ar.
check engine lite came on in my 2012 jeep. I pulled the code and it was for low voltage. If it drops below 10 volts lite comes on. battery was bad.
MPG light unmasked
Tom Dunlap
Any of the mpg and fuel economy gizmos are vacuum gauges in disguise
I learned about them when reading Hot Rod magazine I high school. When I got my ‘70 Chev ¾ ton pickup it had a 4 speed. Instead of a tach I installed a v gauge. Watching the gauge helped me coordinate acceleration and shifting. Hard to gauge mpg increases when I got about 12 mpg but I knew that the engine was operating most efficiently
Re: O.T. Pickup and Auto Dash Boards
AZ in Colorado Springs
What cars have no coolant temperature gauge? I've never owned or rented a car without that. I'm not challenging that, it just makes me curious.
I remember a lot of cars in the 70s had fuel economy meters. Simply a vacuum gauge. I worked at a full service car wash and it was humorous that the gauge would indicate maximum fuel economy when the car was in neutral or park, engine idling, going no place.
More recently, my Durango had a digital gas mileage display. When stopped at a traffic light or warming up in the driveway, the readout said 0 MPG. Much better reflection of reality.
Re: O.T. Pickup and Auto Dash Boards
Mark Nowicki
My 2012 Civic and son's 2013 have no temp gauges.
A driver's car should have the tach as it's primary display, for example a 76 Alfa Romeo GTV.
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idiot lights....
John in NM
That reminds me - I once got in a forklift the boss had rented to unload a flatbed of mesquite from Mexico - I was the only one who'd driven a forklift before. I knew what all the levers did but got really distracted by trying to figure out all the clever little pictograms that some designer figured were better than just using words in any language - english, spanish, german, french even, those would have been kinda obvious!
Re: O.T. Pickup and Auto Dash Boards
John in NM
That's like my mpg on a trip down the mountain - if I stop right at the bottom (where the gas station is) the computer tells me I got 99 mpg! Basically idled all 15 miles down
At least these indicators do take actual miles traveled into account, neither the tach or vacuum gauge can do that - but I still think they are useful if they cause the driver to wonder and ask questions. Idiot lights and computers seem to cause us to not think about what is really going on.
Re: MPG light unmasked
Jason Roehl in Lafayette, IN
I'd be really surprised if the instantaneous MPG gauges on modern vehicles has anything to do with vacuum anymore. With the precision required of the fuel delivery system by the computer in today's vehicles, my money is on a fuel-flow-per-distance calculation.
Jason
Re: MPG light unmasked
John McGaw
Exactly. The Subaru's fuel measurement is derived from the computer controlling the injectors and, since the computer keeps precise control of every pico-liter of fuel being injected, it can say exactly what is being consumed at any given time. I've done the comparison of what the display says my average fuel consumption is vs. what a gallons pumped into the tank and mileage traveled computation says and they match within maybe 2%. Close enough for me.
Re: idiot lights....
Bill Howatt
Reminded me of a computer seminar on the new-fangled graphical interfaces many, many years ago. Presenter carefully made the point that the icons often do not impart much information, if any, to the user. How many times have we hovered over an icon to see the description of what it does?
Bill
Re: idiot lights....
Ray Newman
Speaking of pictograms, all the men's restrooms in the restaurants and business I patronize have pictograms showing how to wash your hands!
Re: O.T. Pickup and Auto Dash Boards
Kevin French
I've never bothered watching the tach even in my Stds shifting on sound. Then again I do look a the tach on my wife's Nissan Versa, in 5th gear it sounds like it needs a higher gear.
Another tangent...
John in NM
I went to Missouri last year to pick up a Maka mortiser (that I still haven't tried yet) and stopped for a sandwich and bathroom break at a JimmyJohns sub store. The pictogram tile in the men's room was definitely "entertaining".
Made me wonder if that was a corporate design decision and the were in all JJ sub stores where ever they may be.... May have to stop and check next time I see one in Albuquerque.
They all do sound like that
Mike L
I have Tach's in both my trucks. With the electronic shifting they leave it in a higher gear to get the RPMS done to save gas. I hate the new shift stratagy on these new vehicles. You hit the gas it shifts down one two or three gears to get you up the hill. Or it tries to pull the hill in the higher gear and lugs the engine.
Re: They all do sound like that
Jim DeLaney, Austintown, Ohio
Had the same situation/problem with my 2018 Toyota Tacoma. Complained to the dealer about it - and also about the throttle response. They found a Tech Bulletin about it, and re-flashed the computer. That solved it. Now I get smoother up/down shifts, more 'logical' downshifts, and a much smoother throttle response.
You might check to see if Ford can do a similar re-flash for you.
Re: O.T. Pickup and Auto Dash Boards
dlwurscher
For those of us where the steering wheel blocks the speedo, when in the down position the tach becomes the speedo (ha-ha)
Re: They all do sound like that
Kevin French
This is a 10-year-old STD Trans.
Even my 04 STD Trans Honda Element I shift a lot from 5th to 5th on the Highway when it's spinning just under 4,000 RPMs
They are shifting as designed
Mike L
I am not having a problem with mine, I just hate the way they all shift anymore. Rental cars from all makes my trucks all shift way to early on the way up and to late on the way down.