[wadge22]

There are different types of automatic transmissions, but even today many of them are still the type with a hydraulic torque converter, which are inherently less efficient than a manual transmission with its friction clutch (a fair amount of the input torque is lost as heat in the torque converter). More and more cars nowadays have dual clutch transmissions, which are an automatic type designed like two manual transmissions next to each other, one for the odd gears and another for the even gears, that are shifted automatically. Because that type uses a clutch (two, one at any given time, generally), it doesn't have the same losses as the hydraulic torque converter automatics.

Then there's the matter of the number and ratios of the gearing, for whichever trans type, with more gears meaning more ability to keep the engine at an efficient rpm (or at an rpm with the best torque, if that's what you're trying to optimize).
Comparisons like the EPA fuel mileage estimates make assumptions about how a manual trans driver will shift to come to their estimate, but a manual trans offers the driver more leeway to choose whether they want to optimize shifts for acceleration or efficiency, assuming the driver knows how to do so effectively. I have no doubt modern computers are very good at selecting shift points, which gives the automatic an advantage over the average manual driver, which may or may not more than make up for the inherent disadvantages of the automatics with a torque converter.

In the end, it all comes down to the specific designs of specific transmissions available in the car or cars you're shopping for, and to a lesser extent to the skills and driving habits of the driver (particularly for the manual). Some models may get better fuel efficiency with the automatic, others may get better efficiency with the manual. Plus, sometimes you can only get a certain engine with a certain transmission, and obviously the engine plays a huge role in efficiency.

One other advantage of the manual trans is that it's a fairly simple device with a well established design, and they are usually reliable. It's also relatively easy to replace the clutch when it starts to wear out, whereas automatics are not nearly as user serviceable. Of course, most modern cars aren't designed to be user serviceable at all.
I personally will stick to buying used early '90s cars with stickshifts, but that certainly doesn't mean it's right for everyone.

[Photos-by-Chas]

It's gradually heading the same way over here, Chas Of course, with electric vehicles the manual transmission will largely become a thing of the past anyway...

Electric vehicles may be the wave of the future, but I think it will be several years, possibly a couple decades or more, before they are the only method of transportation. The necessary upgrades to the power grids, charging stations, the time required to reach full charge and the improvement of vehicle range on a single charge, will all be important to the acceptance and viability of them.

[slartibartfast01]

Becoming very hard to find manual cars here too.
Having said that, I've not found very many environments where a manual car is more useful, so I can understand why cars are mainly auto now.

Many years ago I was a passenger in a Montego Turbo with an automatic transmission. I thought it was an MG but I can't find any reference to an automatic transmission in those. On the motorway it would change down a gear at the slightest touch of the accelerator then change up again almost immediately. Very disconcerting and extremely annoying

Edit. Probably a Vanden Plas

[Lord Lucan]

consumers mostly use automatic transmissions these days. Race car drivers are known for wanting exact control

My car is auto transmission but I can nudge the gear lever up or down which is what I do most of the time in the hills. I'm never very satisfied with the way it changes.

My Ford Fiesta is equipped with Ford’s “high mileage” package, which includes vents to close off the radiator when starting {so engine will warm up faster}, special flaps to improve airflow around the wheels, and a special automatic transmission with a fifth gear which gives better MPG at 50+ MPH {it’s basically what used to be called ‘overdrive’}

That sounds like most UK cars since at least 1980, starting with the 5-gear Austin Maxi. The thermostat in cars' water cooling systems has always shut the radiator out of the circuit until the engine warms up - has the Fiesta done away with the thermostat and has air-side vent flaps instead?

a manual trans offers the driver more leeway to choose whether they want to optimize shifts for acceleration or efficiency, assuming the driver knows how to do so effectively.

I'm more concerned about engine life. Car makers are hell-bent on reducing their published mpg figures (however unrealistic they may be), so auto transmissions are programmed to use lower ratios than are good for engine wear. The cost of having to replace an engine would wipe out any slight savings from forcing the engine to labour up gradients without changing down. I'm not talking about motorway cruising, but about the short sharp rises around where I live. Lady L's car is manual but recommends gear changes on the dashboard display, and its choices are astonishing. I'm an engineer and hearing the labouring makes me feel stressed, let alone the engine.

PS : Regarding the term "overdrive". In olden days, top speed was the main selling point (just like mpg today) - 40 mph! 50 mph! 60 mph!! During development the maker would try different final drive ratios and choose the one that gave the highest speed. This did not (of course) give the most mpg in cruising at intermediate speeds, which is always achieved at a higher ratio. So the more expensive cars offered a second gearbox bolted on the back of the standard one that had two ratios like 1 : 1 (straight through) and 0.8 : 1 (a speed-up). The latter was considered to be over-driving the engine because it required more torque from it at any speed, and the car could not achieve its top speed, but it was more efficient at cruising. But the overdrive box was very expensive (more than the main box) so it made sense to incorporate an overdrive fifth gear into the main box, whether auto or not, which I believe the Austin Maxi was the first to do in the UK at least. I guess that with some auto gearboxes having six or eight gears today, two or three of them are overdrives.

[MarkJerling]

Many years ago I was a passenger in a Montego Turbo with an automatic transmission. I thought it was an MG but I can't find any reference to an automatic transmission in those. On the motorway it would change down a gear at the slightest touch of the accelerator then change up again almost immediately. Very disconcerting and extremely annoying

Edit. Probably a Vanden Plas

Technology has come a long way with autos. In my Discovery, it was clunky, gear changes was slow and, until give or take 78km/h, when the torque converter locked, it was uneconomical to boot. With my F100, I went through two C4 boxes and a torque converter. Expensive maintenance.

With my wife's Ford Mondeo (Fusion in USA and Canada) the auto box shifts like a manual, except much quicker. There's no torque converter and you can drive it as a sequential shift (paddle shifted) manual or let the car do it's thing in auto. It's always in the correct gear and even anticipates downshifts pretty well. Moreover, if you set the speed control it will select the correct gear to keep that speed, uphill and downhill. Plus, the whole thing is sealed and entirely maintenance free for 300,000+ km's.

[Serkevan]

Here automatic transmissions are also becoming more common than they were - mostly because the dual gear finally makes them not terrible (and all my friends still use the paddles to choose gear pretty often - but that's what happens when so many of our region's roads are fit for rallys haha).
Still, you're looking at about 2k extra for the automatic version (which for the typical car is about 10% (!) extra cost)... plus an additional oil change every now and then.

Speaking of cars, I wish my K-1 ran on one battery as long as my Octavia runs on one tank ... With the current fuel prices, I'm very happy that it only drinks 4.7 l/100km (for the Americans, that's a sharp 50 MPG).

[Rondec]

Electric vehicles may be the wave of the future, but I think it will be several years, possibly a couple decades or more, before they are the only method of transportation. The necessary upgrades to the power grids, charging stations, the time required to reach full charge and the improvement of vehicle range on a single charge, will all be important to the acceptance and viability of them.

We will see a mixture of vehicles for a while. I don't think cross country trucking will shift any time soon -- if you need a semi tractor trailer that is available to be on the road 17 or 18 hours per 24 hours, it seems like batteries aren't at that place yet.

We'll see a gradual shift. If you own your vehicle, you aren't going to get rid of it tomorrow, but if you replace it, you are certainly either going to look for a vehicle that gets really high mpg or an electric vehicle, depending on how much you drive. Assuming a driving range of 200 to 250 miles on a charge, I think the majority of people could get by with that sort of range.

Thinking about photography, we see the same thing. Things do shift over time, but it is gradual. There are still an awful lot of SLRs in use and even if people are changing to MILCs, many are continuing to use their SLR lenses on their new cameras with adapters. Not so much revolution as evolution.

[Serkevan]

. Moreover, if you set the speed control it will select the correct gear to keep that speed, uphill and downhill. Plus, the whole thing is sealed and entirely maintenance free for 300,000+ km's.

Huh, this actually sounds very good. The Škoda (well, VAG in general) DSG box schedules an oil/filter change every 60k km. Which isn't altogether too bad, but it's 250€ or so IIRC, so it adds a fair bit of cost.

[reh321]

Here automatic transmissions are also becoming more common than they were - mostly because the dual gear finally makes them not terrible (and all my friends still use the paddles to choose gear pretty often - but that's what happens when so many of our region's roads are fit for rallys haha).
Still, you're looking at about 2k extra for the automatic version (which for the typical car is about 10% (!) extra cost)... plus an additional oil change every now and then.

I live in a very flat area - surrounded by cornfields. In our state capital, they have run a race for over 100 years - that influenced US car racing - that started off proving that a regular car could run 500 miles in a day {an accomplishment in 1911} on a perfectly flat ‘oval’ {actually four straights connected by four turns}. They shift gears there only because of the turns.

added: The first racers tended to have two people - one to drive the car and one to keep track of the cars behind them, but the first winner was a clever guy who figured that he could keep track of the cars ahead of him, so he added a mirror as a light-weight means to help him keep track of track of those behind him; the next year, all the cars were ‘single seaters’ with “rear view mirrors”.

[ThorSanchez]

It's gradually heading the same way over here, Chas Of course, with electric vehicles the manual transmission will largely become a thing of the past anyway...

Some electric cars (including the Porsche Taycan, IIRC) have an automatic two-speed gearbox that makes them somewhat more efficient at highway speeds. There's no technical reason that I know of that you couldn't put a manual in those vehicles. Even if it makes little sense.

You know someone will eventually do that, even if it's a one-off that takes hundreds of hours of labor and many thousands of dollars and makes the car needlessly complex and less efficient.

I'd drive that.

Also, I've read of restomods that swap in a crate electric motor while keeping the original drivetrain including the manual transmission. The latest IEEE Spectrum magazine had an article on a 60s VW Bus they'd done that to. It's crossed my mind to do that to the currently non-functional '63 Corvette in my garage, even if that might be considered blasphemy to a lot of the boomers who lust for a split-window Vette.



---------- Post added 06-22-22 at 09:59 AM ----------

There are different types of automatic transmissions, but even today many of them are still the type with a hydraulic torque converter, which are inherently less efficient than a manual transmission with its friction clutch (a fair amount of the input torque is lost as heat in the torque converter).

Today's torque converter automatics are barely less efficient than a manual. Actually, modern 7, 8, even 9-speed automatics are probably more efficient than their typically 6-speed manual equivalents because they are programmed to shift at optimal points. And they never forget that they've been in 4th or 5th for the last 10 minutes, as I'm sure almost all manual drivers have.

I drive a manual because it's more fun and engaging, but automatics are typically more efficient and accelerate faster. My '14 Audi S4 is spec'd at 4.6 seconds 0-60 mph with the dual-clutch automatic, and 4.9 or 5.0 with the manual.

[reh321]

Some electric cars (including the Porsche Taycan, IIRC) have an automatic two-speed gearbox that makes them somewhat more efficient at highway speeds. There's no technical reason that I know of that you couldn't put a manual in those vehicles. Even if it makes little sense.

You know someone will eventually do that, even if it's a one-off that takes hundreds of hours of labor and many thousands of dollars and makes the car needlessly complex and less efficient.

Today's torque converter automatics are barely less efficient than a manual. Actually, modern 7, 8, even 9-speed automatics are probably more efficient that their typically 6-speed manual equivalents because they are programmed to shift at optimal points. And they never forget that they've been in 4th or 5th for the last 10 minutes, as I'm sure almost all manual drivers have.

Whether it would make sense would depend solely on efficiency. It is needed for gasoline engines because they have an actual torque curve - which goes up, then down - but an electric motor makes maximal torque at zero rpm.

[ThorSanchez]

Whether it would make sense would depend solely on efficiency. It is needed for gasoline engines because they have an actual torque curve - which goes up, then down - but an electric motor makes maximal torque at zero rpm.

The efficiency of an electric motor does fall at high rpm, and a single-speed electric car usually has a lower top speed than its ICE cousins. As I mentioned before the Porsche Taycan has a two-speed gearbox, which is claimed to boost overall efficiency by 5% and allows for a top speed of over 160 mph. At the expense of some complexity, the need to design a transmission that can handle the torque, and, presumably, the need to eventually change the transmission fluid.

[photoptimist]

Today's high gas prices will likely accelerate the switch to electric vehicles. On a $/mile basis, electric vehicles in the US pay roughly the equivalent of less than $2/gallon.

[Serkevan]

Today's high gas prices will likely accelerate the switch to electric vehicles. On a $/mile basis, electric vehicles in the US pay roughly the equivalent of less than $2/gallon.

Meanwhile, my last refuel was at nearly 8$/gallon. Yay.

(The situation is basically untenable for many here - keep in mind that average gross salary in Spain is 24k€ a year. My friends with long commutes are really feeling the sting)

That said, I'm 100% sure that switching to electric vehicles en masse would make the price of electricity skyrocket. Call me cynical.

[BigMackCam]

Today's high gas prices will likely accelerate the switch to electric vehicles. On a $/mile basis, electric vehicles in the US pay roughly the equivalent of less than $2/gallon.

Meanwhile, my last refuel was at nearly 8$/gallon. Yay.

(The situation is basically untenable for many here - keep in mind that average gross salary in Spain is 24k€ a year. My friends with long commutes are really feeling the sting)

GBP £1.99 per litre at my local Esso this morning... which works out to USD $9.27 per US gallon. I've basically stopped using my car except for essential journies (grocery shopping, hospital / doctor / dentist / vet visits etc.), and one short recreational trip per week for my folks and I (just a few miles to local picnic spots). Crazy times...