Fewer than 3% of cars sold in the U.S. have manual transmissions • Hacker News Board

Re: Fewer than 3% of cars sold in the U.S. have manual transmissions

#461

Post by Steuard » Thu, Nov 17, 2016, 1:16 PM UTC

72deluxe wrote: post #361

mbrookes wrote: post #353

Earlier quoted context omitted.

Coasting in neutral or with the clutch disengaged is both more dangerous and less efficient then engine braking. In the UK you will fail your driving test if you coast, and in some countries / states it is illegal - with good reason. Just google it - not a single article supporting your argument.

But if you're coasting down a hill and not braking, your engine is idling and you're making use of gravity. The engine will be turning over at ~1000rpm instead of 2000rpm in my diesel. Understandably it is dangerous as you are not in control of the transmission and therefore the wheels, hence the failure in the UK. But I got through some incredibly scarce times by coasting a bit on the commute to work... With automat…

Every automatic car I've ever seen has had the ability to downshift to engage engine braking. (Even the CVT in cars like the Prius has an engine braking mode.) I've seen advocates of manual transmissions cite a lack of engine braking as a reason to switch in multiple conversations, so I've gotten the impression that a lot of people just aren't taught how to drive an automatic properly. (Do they not talk about this in driver's ed? I don't even remember anymore.)

Re: Fewer than 3% of cars sold in the U.S. have manual transmissions

#462

Post by tim333 » Thu, Nov 17, 2016, 1:17 PM UTC

bitL wrote: post #339

I never understood how to use automatic transmission in snowy/icy conditions. To me it's basically a lottery. With manual transmission and clutch I can actually recover from a slide almost immediately (the moment you start sliding you disengage transmission right away with clutch and do initial correcting maneuver which you cut short the moment you feel any kind of traction in order not to oversteer; it takes some pr…

You can avoid skidding on the corners by going a little slower? I drove an automatic Camry a while in a ski resort and the only real problem was when the gradient got too steep so you couldn't get enough grip to get up which is not a transmission problem.

Re: Fewer than 3% of cars sold in the U.S. have manual transmissions

#463

Post by Yaggo » Thu, Nov 17, 2016, 1:19 PM UTC

vmarsy wrote: post #104

henrikschroder wrote: post #46

I got my driver's license in Sweden, and the official driving handbook completely worships manual transmissions, and makes several untrue claims about how much better they are than automatics. You can choose to do your road test in an automatic, but that'll earn you a restriction on your license, barring you from driving a manual. It's probably fair, but almost everyone (myself included) chooses to practice in manual…

>when automatic transmissions are consistently outperforming humans at fuel efficiency Do you have data to back this up? Unless you're driving a dual clutch "dry" transmission or a CVT, because of Physics, an automatic transmission will always be less efficient. The Automatic transmission Torque converter [1] will waste some of the energy provided by the engine, especially with city driving. Also, most automatic cars…

> Do you have data to back this up?

I think this is widely known fact for modern cars. Automatics (may) have more gears & can consistently shift more optimally than average human driver, making up the loss of "wet" torque converter.

Re: Fewer than 3% of cars sold in the U.S. have manual transmissions

#464

Post by codingdave » Thu, Nov 17, 2016, 1:19 PM UTC

I'm pretty satisfied with the way my Subaru works -- I leave it in automatic most of the time, but I do have a manual option that I can use when going up/down hills, in icy conditions, or whenever I want. I'm sure other models have the same feature. It seems like the best of both worlds.

Re: Fewer than 3% of cars sold in the U.S. have manual transmissions

#465

Post by smileysteve » Thu, Nov 17, 2016, 1:20 PM UTC

henrikschroder wrote: post #230

nostrademons wrote: post #206

Earlier quoted context omitted.

It's not the fuel required by the engine, it's the engine braking. Going down a hill with clutch disengaged, the Accord would accelerate. With clutch engaged, it would slightly decelerate. That's fuel that the engine doesn't need to burn to accelerate it back up to cruising speed. Ditto when coasting to a stoplight - with clutch disengaged (or in neutral), it would coast for a longer distance, which - if you're caref…

Anecdotal, but I did some tests in my previous car (a 2014 Mercedes, automatic) and it coasted really, really, really well. In drive, downhill, on the freeway, feet off all pedals, it would accelerate as much as if I put it in neutral, so I think its software and transmission allowed it to perform as good as a manual in that situation. Not calling you out specifically, but a lot of people arguing for manual transmiss…

Automatics don't engine brake the same way, the torque converter is only fully engaged when it has some pressure buildup, so it will slip (and not maintain fuel cut) when coasting whenever the wheel speed won't maintain the pressure.

To test, watch your rpm when you left off the gas, if it drops to ~750-1000 rpm, your torque converter is slipping (as designed) and not maintaining fuel cut.

To agree with you, I think the comments in this thread started from a manual transmission standpoint and then everybody thought it applied to automatics.

Re: Fewer than 3% of cars sold in the U.S. have manual transmissions

#466

Post by codingdave » Thu, Nov 17, 2016, 1:23 PM UTC

kweinber wrote: post #7

Manual shifting is neither possible nor even relevant in electric cars or cvt (continuous variable transmission) cars. Their rise will be the true end of the stick shift.

That is completely dependent on the design of the engine. There is no reason that an electric motor cannot be hooked to a transmission. It just doesn't need it as badly because they can handle sustained high RPMs, and in many cases, are specifically designed for high RPM operations. So it makes sense to keep things simple, and leave out the transmission, and that is what we are seeing right now.

But as electric cars become more common, they will need to be able to handle all types of driving, including steep slopes, which is a very common reason to stay in a lower gear. There will be demand for such a function, even if not in every vehicle.

Re: Fewer than 3% of cars sold in the U.S. have manual transmissions

#467

Post by Annatar » Thu, Nov 17, 2016, 1:23 PM UTC

henrikschroder wrote: post #288

vmarsy wrote: post #104

Earlier quoted context omitted.

>when automatic transmissions are consistently outperforming humans at fuel efficiency Do you have data to back this up? Unless you're driving a dual clutch "dry" transmission or a CVT, because of Physics, an automatic transmission will always be less efficient. The Automatic transmission Torque converter [1] will waste some of the energy provided by the engine, especially with city driving. Also, most automatic cars…

In another subthread to this I posted numbers for various models of BMW, Audi, and Mercedes. I could find one Mercedes model where they report worse fuel economy and slower 0-100km/h acceleration time for the version with an automatic gearbox, in all the other models I looked at, the manufacturers rate the automatics as more efficient and having better acceleration than the manuals. These are of course high-end curre…

Please bear in mind that manufacturers currently self-police and that they test under artificial conditions. Hence, there have already been several scandals with Honda, Ford, Hyundai and Volkswagen either manipulating, or falsifying results; not even the onboard computer can be fully trusted: the only precise measure is noting how many liters were put in and how many kilometers were driven on that quantity, and that only on the spec tire size and with the assumption that the odometer is correct.

Re: Fewer than 3% of cars sold in the U.S. have manual transmissions

#468

Post by smileysteve » Thu, Nov 17, 2016, 1:23 PM UTC

Steuard wrote: post #461

72deluxe wrote: post #361

Earlier quoted context omitted.

But if you're coasting down a hill and not braking, your engine is idling and you're making use of gravity. The engine will be turning over at ~1000rpm instead of 2000rpm in my diesel. Understandably it is dangerous as you are not in control of the transmission and therefore the wheels, hence the failure in the UK. But I got through some incredibly scarce times by coasting a bit on the commute to work... With automat…

Every automatic car I've ever seen has had the ability to downshift to engage engine braking. (Even the CVT in cars like the Prius has an engine braking mode.) I've seen advocates of manual transmissions cite a lack of engine braking as a reason to switch in multiple conversations, so I've gotten the impression that a lot of people just aren't taught how to drive an automatic properly. (Do they not talk about this in…

Very few drivers in the U.S. know when to turn overdrive off or use a selective gear.

Re: Fewer than 3% of cars sold in the U.S. have manual transmissions

#469

Post by ecopoesis » Thu, Nov 17, 2016, 1:24 PM UTC

vmarsy wrote: post #104

henrikschroder wrote: post #46

I got my driver's license in Sweden, and the official driving handbook completely worships manual transmissions, and makes several untrue claims about how much better they are than automatics. You can choose to do your road test in an automatic, but that'll earn you a restriction on your license, barring you from driving a manual. It's probably fair, but almost everyone (myself included) chooses to practice in manual…

>when automatic transmissions are consistently outperforming humans at fuel efficiency Do you have data to back this up? Unless you're driving a dual clutch "dry" transmission or a CVT, because of Physics, an automatic transmission will always be less efficient. The Automatic transmission Torque converter [1] will waste some of the energy provided by the engine, especially with city driving. Also, most automatic cars…

Automatics and manuals have basically the same efficiency. All numbers from fueleconomy.gov

2016 Ford Fiesta FWD 4 cyl, 1.6 L - Auto: 27/36, Manual: 27/35

2016 Ford Focus FWD FFV 4 cyl, 2.0 L - Auto: 26/37, Manual: 26/36

2016 Volkswagen Golf 4 cyl, 1.8 L - Auto: 25/35, Manual: 25/36

Re: Fewer than 3% of cars sold in the U.S. have manual transmissions

#470

Post by po » Thu, Nov 17, 2016, 1:26 PM UTC

TeMPOraL wrote: post #395

sshanky wrote: post #128

Earlier quoted context omitted.

In modern cars, disengaging the clutch (or using neutral) when coasting (toward a stop or down a hill) is less efficient than staying in gear. This is because it takes some fuel to keep the engine idling, where staying in gear allows the computer to completely cut fuel flow, as long as the forward motion is keeping the engine turning.

Oh so that's what was happening... Two days ago my friend and I were driving a rented car and we've noticed that when coasting, the computer said the fuel consumption is 0, but when the friend disengaged the clutch, the fuel consumption actually went up (!) to some value. We've been wondering what's going on, and we actually suspected a software bug in the fuel consumption indicator. Thanks!

Not only that but staying in gear when going down hills or slowing down will reduce the wear on your breaks by using the inertia of the engine to slow the car instead of break pad friction/heat.