I only drive manual cars (have tried driving automatics, but just can’t do it). I look at the tachometer quite often. I’m not savvy, or interested, enough to know by sound if I need to switch gears, the noises are different with every engine, anyway, and I wouldn’t trust such vague methods at any rate. I just glance at the tachometer and it tells me exactly how it is.
Living in the UK I always drive manuals. Modern cars are more refined (quieter) so at normal revs you don’t always hear the engine clearly over wind and road noise. The rev counter let’s me know what the engine is doing.
I usually try to keep the revs low (for better fuel economy) but I need to keep it in the powerband so I’m not letting the engine labour which is less economical.
If I am at the bottom of the powerband I won’t be labouring but most roads these days are overcrowded. If I need to overtake I need to be an extra 500 or 1000 revs to ensure swift acceleration.
Another one is on snow and ice. If my speed is constant but the revs keep surging I know the wheels are spinning. Serves as a warning about the grip.
I most certainly DON’T consider myself any sort of great driver. But I find a Rev Counter part of driving. It’s the difference between simply being moved from A to B and enjoying a drive while trying to drive well.
TCMF-2L
I’ve driven manual cars and motor cycles, and I’ve only ever used the tacho, when I’ve had one, for the same thing I use the scenery for: to look at when I’ve got nothing better to do.
My current automatic car has much better noise insulation, and perhaps I’d use the tacho if it was manual. But it would make a very poor manual car anyway: you’d have to churn through the gears to keep it in the power band.
I used it a lot in my manual car when I was a new driver. Now I’m more experienced I use it a lot less as I use the sound of the engine. However it still comes in useful every now and then especially when the engine is hard to hear.
nods seems reasonable. I’m not one of those arrogant folks who says everyone ought to drive the way I do.
To clarify, though, I don’t shift back and forth (much) in bumper to bumper traffic; what I do is drop the auto trans into a range that keeps it in low or medium-low gear. That lets me add gas when the stop-&-go traffic jam is in “somewhat of a go” mode, but when the cars in front of me inevitably sludge down to a crawl again, I just take foot off the gas and it rapidly decelerates without me using the brakes. In Drive, in contrast, the car would shift into 3rd or 4th, I’d almost immediately have to brake, OR after gradually oozing up to 20 mph the cars in front of me would suddenly find room to get up to 45 but my car, having shifted to 4th because I was barely pushing down the gas, would be relatively unresponsive to a gentle gas-pedal push (gear too high for that) and would downshift with an overcompensating burst of speed if I gave it more (would get up to 45 then upshift immediately once I got there) then the cars ahead would start sludging again within seconds and I’d have my foot on the brake.
Likewise for merging, automatics in Drive aren’t mind-readers; I don’t really need to accelerate so hard my passengers’ heads are slammed back against the headrests but I want more than the acceleration curve I’m going to get if it stays in the gear that it’s in. If I hit the gas hard enough to make the vaccuum change effect a downshift in the Mitsubishi, that’s more acceleration than I need, whereas an explicit shift to 3rd lets me easily coast up to 60 mph without my passengers thinking I’ve got a Mario Andretti / Walter Mitty thing going on in my head. Or, in contrast, in the old Pontiac, hitting the gas hard would drop the old Turbo-Hydramatic from 3rd to 2nd, but I actually want 1st to get from 30 mph to 50 mph and explicitly dropping in to L does that. It’s a big heavy car with highway gears and first gear is good up to 60 mph, but the automatic shifting in Drive isn’t tailored to downshift two gears’ worth.
All of the prior posters are correct, but in my view the main point of it is that as a middle aged guy on those rare days when my testosterone gets up, I can drive my mid-sized SUV like I am A.J. Foyt on the interstate, red line it, and pretend that I am not slowly descending into old-man-hood.
In heavy commercial trucks, the tachometer can also help you float the gears (shift without using the clutch.) I can mostly do this by sound and feel alone at this point, but when you’re starting out, it’s useful to know the specific RPMs at which you can drop the shifter into neutral (sometimes you have to feather the throttle a little to find the sweet spot) and then put into the next gear without having to even press the clutch at all.
The other day when it was still nice enough to drive with the windows down I stopped at a light in the center of three lanes. The light changed and I accelrate to the speed limit – 30 – and settle down. Meantime I’m hearing someone with a four-banger, manual transmission, fart can exhaust, climbing up through the gears and I swear he was at redline before each shift.
I check the inside mirror, nuthin’. I check the right mirror, nuthin’, then finally by craning my neck I can see him creeping up on my right side. All that sturm und drang and he’d made to maybe 32mph.
Reminded me of Mr. Bean stealing a moped.
Fun fact: yes it does. Shows how often I look at it, I guess. And how much good it does me.
The trucks I drove back then had gearboxes that lent themselves very well to this technique. For the most part, the clutch was only needed when pulling away from a standstill. With twelve gears to play with (although only eight were used in normal driving), it was always possible to pick the right gear for the speed.
This must be with a poorly designed gearbox. My car, with six to choose from, usually manages to choose the correct gear at whatever speed I am driving. I do use the paddle to force a downshift at junctions, but otherwise it is left alone. In fact I only have P,R,N,D and S anyway.
My first two cars were both stick. The first, a Volvo 240 wagon, didn’t have a tach so I learned to shift by engine noise and general speed. My Subaru Impreza did have a tach, but I mostly only used it for very specific driving conditions. For example, nasty hill starts where you rev the engine higher than normal with the hand brake on and then let out the clutch while releasing the brake. Also in hilly terrain where I would have to upshift to have enough power to climb. Still don’t want to run it too close to redline for too long.
What frustrates me is that my 5-gear automatic Forester has a tach I don’t need but has no temperature gauge, just a dummy light. I don’t need the tach even in sport mode with clutchless shifting but I’d like to actually have some idea of what my engine temp is.
It’s been a while since I’ve owned a car with a manual transmission; every one I did own had a tach.
That said, I can’t imagine looking at the tachometer every time I shifted.
Or ever, actually.
mmm
I remember hearing a discussion on CarTalk about why cars with auto transmissions have tachometers. Tom & Ray were of the opinion that there was a space on the instrument panel that needed to be filled when the analog clocks were replaced with digital. I’m old enough to remember a clock dial just left of the speedometer; makes sense to me.
A lot of automatic transmissions now have a clutchless manual, aka manumatic, mode. On my car, if I push the shifter to the left when it’s on D, it becomes an up/down paddle shifter. I’ve yet to have a need or desire to use the mode, but it’s there, and a tach would probably be useful.
Just working from memory, pre-1990 I remember hardly ever seeing a tach in a US mass market passenger car except on sold-as-sporty models, and not necessarily even then. And that included manuals – grew up seeing people I rode with in cars with manuals shifting by sound and feel.
OTOH gotta say, the late 60s through early 80s instrument clusters in standard American cars were notorious for the paucity of real instrument readouts. You got gauges for speed, fuel… and sometimes not even the temperature was gauged, as in this one. Helped the J.C. Whitney catalog sell a lot of add-on gauges.
Nope. Even in my quiet car, where I can barely hear the engine, I can tell if I’m accelerating or decelerating, which is all you really need to know in normal ‘manual’ operation.
Sure, if you didn’t have a fuel use indicator, or wanted to operate at the red line, you could think of a use for the tachometer, but no, when I want use the “manual mode” on my automatic, it’s because I’ve got something else to think about, that precludes watching the tachometer.
I’ve found this handy on highway on-ramps, particularly twisty ones like this one. It’s useful to be able to hold the car in a lower gear through the turns rather than inducing a downshift under load by stepping hard on the accelerator as the final turn opens up. Likewise for 270-degree cloverleaf ramps: it’s useful to have the transmission in second or third gear before the cloverleaf ends and you need to step on the accelerator. The ability to force the car downshift before the engine is making torque is useful because it eliminates the jolt you would otherwise get when the car decides to downshift after you step on the gas; this avoids compromising traction in inclement weather, and it also provides your passengers with a smoother ride.
The tach is handy in this mode, though with electronic rev limiters these days it’s not quite as critical as it might have been a few decades ago, when you could overrev your engine if you weren’t paying attention.
Even if you drive by sound of the engine rpm’s the tach is the way you relate sound to actual rpm’s. Downshifting is one such reason for a tach, to know how fast you are spinning your engine to slow your car. Also putting the tach in cars as almost standard came before computer control, thus is was possible to redline a automatic back then, but now the computer will fight you on it every step of the way. Additionally in autotranny’s of the past the tranny ‘recommended redline’ was sometimes below the engine rpm’s. Knowing the engine rpm’s was helpful for the above. Yes not necessary but really any gauge is not necessary, just helpful info.
On my Subaru Outback which is automatic, but with manumatic shifting mode, if you hit the red line while in manumatic the computer would not let it go further, the rpm needle would just bounce off the red line as engine power is reduced (I believe by holding back the spark). If one attempted to shift into a condition to exceed redline the car would simply beep a sour note at you and stay in the current gear. In fully auto mode at WOT it would shift at redline. But again these modern cars have computers to do this for you, in days gone by getting an automatic beyond redline was not only possible but the tranny itself sometimes was not recommended to be spun at redline rpm’s (especially during the late 70’s > 80’s when car manufactures were still figuring out efficiency.
I’m not sure if this has been mentioned yet, but a tachometer would have been quite helpful when I was learning to drive a clutch (my first car). The gear changes become natural after a while, but your first time behind the wheel, you have nothing to relate it to. I remember my eyes being glued to the speedometer in my ‘73 Pinto to judge my gear changes. A tach would have made the transition to changing by feel or sound a lot easier.