The manual gearbox was once the more efficient choice for your car’s transmission. Automatic transmissions wasted power in sloshing fluid around, and typically had fewer gears. Meanwhile, the manual transmission promised a direct mechanical connection between the engine and the drive wheels. For decades, if you shifted a stick well, you could easily drive more miles per tank than a similar vehicle with an auto. That’s not the case anymore, though. Technology moved on, and it’s actually possible to pinpoint when autos became the efficiency kings of the car world.
The Environmental Protection Agency (EPA) has made fuel economy its business over the years. Today, it tracks all kinds of data and statistics about cars to better understand how to cut emissions and improve fuel economy. It publishes these findings annually as the EPA Automotive Trends Report, and the 2023 edition is a doozy. It’s got all kinds of fun facts about automotive technology and how it’s changed over the years, and that includes excellent insights on gearboxes and efficiency. The organization begins with some context, mentioning the importance of friction reduction and number of gears (also called “speeds”):
There are two important aspects of transmissions that impact overall vehicle efficiency and fuel economy. First, as torque (rotational force) is transferred through the transmission, a small amount is lost to friction, which reduces vehicle efficiency. Second, the design of the transmission impacts how the engine is operated, and generally transmissions with more speeds offer more opportunity to operate the engine in the most efficient way possible. For example, a vehicle with an eight-speed transmission will have more flexibility in determining engine operation than a vehicle with a five-speed transmission. This can lead to reduced fuel consumption and CO2 emissions.
As is obvious in the EPA’s report, the biggest change to transmissions over the last few decades has really been in the number of gear ratios. Back in 1980, where the EPA’s relevant data starts, the three-speed automatic was the most popular gearbox in new cars. Across models with and without lockup torque converters (a lockup torque converter helps to reduce energy that would be wasted in sloshing fluid by using a clutch to turn the fluid coupling into a direct mechanical connection), three-speed autos made up the greatest proportion of all sales, across cars and trucks. In that same year, manual gearboxes with four and five speeds were the most common. Fast forward to 1999, and the four-speed automatic with a lockup converter was the most popular transmission by far, seen in over 80% of new cars and trucks sold. The five-speed manual was the most common in this year, with four-speeds all but disappearing.
The plot above shows the types of transmissions found in typical cars between 1980 and now, with M standing for manual (M4 is a four-speed, M5 is a five-speed, ect.), A standing for automatic, and L standing for automatic with a Lockup torque converter).
Looking at the right side of that plot, it becomes obvious that, in recent years, manufacturers have been adding more gears to their automatic transmissions. Like, way more gears. Over a decade ago, Top Gear joked about a Lexus with eight gears, but it’s only gone crazier since then. Automatics with nine and ten speeds are now common, with continuously variable transmissions also becoming highly popular as well.
On the manual front, six speeds are now more common than five, and there are a handful of seven-speed manuals out there, too. The EPA’s plot below shows how average gear-count has changed for autos and sticks.
It’s probably not surprising that, despite there existing other factors like internal friction, the number of available ratios has a close relationship with overall efficiency. As the EPA mentioned, the more gear ratios you have, the more you can keep the engine in its most efficient operating range in all driving conditions, and that’s huge.
Manuals used to have the edge in this regard. They used to have more gear ratios, and especially compared to some early autos, human drivers could be better at picking the right ratio for the given conditions. However, there’s a crossing point in the data around 2011 to 2012. At about the same same time that the average number of gears in an automatic eclipsed the average number of gears in a manual, overall fuel economy numbers for automatic cars started to become higher than for manual cars (the data “[compares] the fuel economy of automatic and manual transmission options where both transmissions were available in one model with the same engine”). The autos had been catching up for a long time, and finally came out on top. Where in 1990, automatic cars were on average 5% less fuel efficient compared to their manual counterparts, by 2022, they were over 5% more efficient.
Here’s the EPA’s look at the fuel economy difference between autos and sticks over time. You can see that automatics became more efficient right around 2010:
So to everyone wondering, including me and this Reddit user named FiveCatPenagerie, we finally have a date when the auto became the MPG superior.
It bears noting that the EPA’s data on this matter will need further finessing in future years. The rise of EVs, many of which have been classified as “single-speed autos,” has seen the average number of gears in automatic vehicles dip in the 2022 data. Realistically, this needs to be split off into its own category in future.
In any case, it’s funny to see it all laid bare. The manual hasn’t been the superior option in any real technical sense for a long time. Instead, it’s like vinyl, or cassettes. It’s the fun old-school way of doing things that we love for its own sake. And there’s nothing wrong with that.
[Ed Note: The report also mentions that certain engines tend to be mated with certain transmissions, which is something that I knew but never really thought about. From the EPA:
For model year 2022, diesel engines were most often paired with a ten-speed lockup transmission, with some eight speed transmissions and a few 6 speed transmissions. Gasoline engines were paired with a wide variety of transmissions, including CVTs, lockup transmissions from ten to five speeds, a small number of manual transmissions, and a small number of non-lockup transmissions (likely dual clutch transmissions). Hybrids and PHEVs also used a wide array of transmission technologies, as there are many hybrid and PHEV engine and transmission designs on the market. EVs are generally designed without a traditional transmission and utilize a single speed design. However, a limited number of high-performance EVs do have a 2-speed transmission.16
Interesting. -DT]
Image credits: EPA
Top graphic image credits: ZF (transmission); Juicy Fish (Freepik); Ford
You forgot about the technology that really was the reason that automatics became more efficient than manuals: the digital throttle. This allowed the automatics to use wide throttle openings in tall gears without downshifting, which before only manuals could do. Engines are most efficient at wide open throttle at the torque peak, once you add the car in to the equation it usually means a lot of short shifting low rpm high throttle opening almost lugging of the engine. So much lugging that people driving manuals would never put up with. Cars with even 4 speed autos were higher geared that 6 speed manuals in the same model and engine because manual drivers would never use top gear and lug their engine. Digital throttles are also the reason that cheap manuals suck because of rev hang that emission standards incentivized. Engines emit more emissions during with fast changing throttles, which is why the fast changing throttle are reserved for only the top models.
I prefer a good 4 speed slush.
Does the efficiency calculate in all the required maintenance that automatics require that buyers ignore, and then have to replace their transmissions at like 80-150k miles?
Because I find driving cars without grenading their transmissions and having to replace them more efficient.
The autotragic’s maintenance requirements or reliability are a 2nd (or 3rd) owner’s problem, which is then counted as a “used car problem”, so it doesn’t negatively impact reliability numbers for a given car (of course some fail way before warranty is over *cough* -Honda automatics and Nissan CVTs-*cough*, which is basically unheard of for manual transmissions).
But yeah, manuals usually don’t need maintenance for the life of the car, as in ‘by the time you need to do anything the car is already sitting in a junkyard’. Even if you never change the trans fluid for 200k miles it might lead to notchy shifts but it won’t leave you stranded like an auto would, and clutches usually last longer than that (unless you drive riding the clutch in traffic, but that’s just a shit driver issue).
I drove manual transmissions for twenty-two years before minivan life changed that. I always wanted a 6th gear in my SHO and have been drooling over a good 6-speed manual trans ever since I became aware of them. Unfortunately, no one in my family commutes daily by car. I take a bus, and my spouse works from home. When I test-drove an Integra recently, I realized that if one does not practice a manual trans to the point of comfortable competence, it is not a practical option. I can’t expect my spouse and teen child to be comfortable driving a manual trans any time soon.
My manual dream is dying. We’ll probably have autos until I possibly purchase a manual as an empty nester. (Maybe a nice Civic type R…..)
Thanks for listening. I’m still mourning this realization. That said, a good engine paring with an auto trans can go a long way toward enjoyment.
Then teach them, this americwn midnset of manuals being impractical is totally bogus. How come newbie trainees learn on it while getting a grip of traffic at thw same time, but you act like they couldnt learn it? Teach them, own only manual cars, it will become second nature within few months and they will master it withinna year.
Dont give up. Because if you do, you also are killing that dream, so dont dream on, just do it, make them drive it by gently learning them, make it a fun exercise between you and your wife on a weekend, then expand to doing swotching as you drive your new Acura integra or other mt car.
Calling the single-ratio speed reducer in an EV an “auto” is really putting a weird spin on it. As I said, it’s a speed reducer with an automated clutch. For parts count it’s hard to beat; having a primary mover that is perfectly comfortable from 0 all the way up to 18,000rpm and can hold 9000 all day long, does simplify certain engineering issues.
Aren’t some of these newest automatics essentially fully automated syncromesh transmissions? The old torque converter that made clutching unnecessary at low speeds has been supplanted by automated clutches, and they use the three-shaft design of a manual rather than the coaxial layout of a traditional automatic? Or am I misremembering.
The manual transmission still has the least amount of parasitic loss. Comparing averages of vehicles that are in the market can lead to false conclusions. Manuals represent a very small market share and are more likely to be paired with high performance options and different final gearing for enthusiasts. Of the automatic options the dry clutch dct is the most efficient but too many people have only driven slushboxes so they dont understand how to drive them. It ends up creating a bad experience with dry clutch dct’s and unfortunately it looks like it didnt go farther.
It might be more correct to say that automatics have become so good the average car with one is now more efficient than the average car with a manual but its not strictly due to transmission efficiency.
check out chapter 5
https://nap.nationalacademies.org/catalog/21744/cost-effectiveness-and-deployment-of-fuel-economy-technologies-for-light-duty-vehicles
All things being equal, manual transmissions will always be more efficient with a competent and equivalently fast operator than an automatic, due to parasitic loss and weight considerations. However, all things are not equal, as the greater number of gears and faster shift speed in a modern automatic allows for the engine to remain in the most efficient areas of its power band. The effect on fuel economy can be seen by looking at the EPA MPG of cars that offer both an automatic and the manual – nowadays, the automatic gets better fuel economy.
I wonder if the decline of the manual trans is partly driven by the EPA. I could see the agency taking a standpoint that manuals are bad because the driver picks the gear, as opposed to a computer which they can easily regulate. The agency then pushes regulations that make manuals difficult for manufacturers to offer.
I don’t think its even that complicated. They have just set high economy standards, and autos are now the way to get them
Yeah, the EPA makes a lot of assumptions about “normal driving” when they compare manuals to automatics, so I don’t treat them as gospel by any means. Yes, computers are probably getting to the point that they can at least on average match a good human with the same number of gears.
Anecdote: One of my inlaws bought one of the first Highlander hybrids, but tends to mash the gas to go and mash the brake at the last minute to stop. They are definitely NOT going to see the EPA numbers for that hybrid automobile, since their habits are not optimal.
Vinyl and cassettes are not quite the same, fidelity wise. Just saying.
As most of us I grew up with manuals and drove manual exclusively until somewhere around 2014. Now I have 2 7 speed automatics (lockup) with manual flappy paddles on the steering wheel and except for nostalgic and financial reasons I don’t see a reason to want any manual back.
Manuals have their place in certain vehicles, but no way I am going to drive more fuel efficient in a manual in stop and go traffic in the city. Even on the highway the auto box will pick the right gear while I think of other things. Before I know it I’m in 7th gear while doing a measly 110 km/h.
The automatic transmission is heavy and maintenance can be expensive, much more expensive than a manual. But modern automatics have become pretty solid as well and I don’t expect to drive more than 60-80k miles with one car so I don’t require some sort of system that can last 200k miles – e.g. some Toyotas. It’s great they can last so long, but I don’t want to drive 200k miles in a Toyota unless it was an old style Supra or something.
I understand the purists, but manuals anno 2023 just aren’t more efficient than an automatic in 2023 because the automatic will almost always shift in the right gear at the right time while you with the manual will be too early or too late. There are the fuel savings, not in the drive train itself. The program.
I can put my 2 automatics also in manual (or set the highest gear) and sometimes I just forgot I did that and then after a few minutes I think … “why is there so much noise” and I find the car was set to (no higher than) 5th gear by me, while we’re driving over 100 (km/h). Allowing the car to do his thing immediately results in an upshift to 7th and we continue to cruise along happily at around 1400 rpm.
Interesting detail ; to achieve the 0-60 mph numbers from the magazines with a manual box you really have to do your shifts very very well, close to dumping your clutch on every shift. With an auto you can just stomp the throttle and you’ll see the manufacturers numbers over and over again.
Is it more ‘engaging’, a manual? Sure. But don’t say you don’t get tired of changing gears in traffic, day in, day out.
*Note not every automatic is the same. I’ve driven some horrible automatics and some very very smooth ones. Some are programmed by early 80s AI it seems and some likely had a human with understanding of how cars actually should move forward. So even if you have two 7 or 8 or 9 speeds automatics ; they can both drive completely different.
No, the comparison with vinyl is a perfect one. That audiophile – or audiophool, rather – may prefer vinyl for all sorts of reasons, but that does not make it the more high fidelity medium.
Vinyl’s actual, realistic (in any system of any type, literally could spend billions of dollars if you wanted) fidelity to the original signal (dynamic range, frequency response, harmonic distortion of any kind, noise, so-called ‘resolution’ – is so inferior to digital storage mediums that you can literally throw a decent quality (i.e. Redbook PCM or better) analog to digital and then digital to analog conversion loop in the signal of the turntable output, and it would be entirely inaudible to any human listener.
The literal plastic grooves in a vinyl record just can’t be created nor tracked in a way – even discounting the pops and cracks from dust and scratches – that is accurate enough that a human cannot perceive it. That is not the case with digital audio storage.
Much as in the same way that film resolution is limited by silver halide grain size, vinyl record performance is limited by the ability to cut, press, and then track with a needle tiny little grooves in a piece of plastic, which are worn down every time the needle passes them. There are laser records players without a needle – but that record still has to be pressed in the first place, and the tooling cut.
My ancient $40 smartphone has B&O tuned quad 32 bit D/A converters which really comes in handy for my Napster era collection of 128 kbps MP3s.
That makes me feel really good about owning a manual transmission car from 2003 and an automatic from 2011, kind of get the best of both worlds… however, the 2003 is much more efficient than my 2011 car!
This is a great article and very interesting. Thank you. I think what would add to it is a paragraph or two about how programming the transmission has also affected efficiency. I’m sure that’s been a factor.
Also, a companion article about AWD… as it seems that once upon a time, such things were always huge drags on fuel economy and now they are much less so.
One more edit: the comparison to vinyl is a poor one. Lots of serious people consider vinyl inherently better. I read a long, long article about a person with literally $300K of audio equipment who only spins vinyl. But why? the interviewer asked…don’t you hear pops, scratches, etc? The audiophile’s response? When you hear live music, you also hear the coughs, claps, and other noise of the audience, but does that mean that live is somehow worse? Of course not. Well, the analog reproduction of vinyl through tube equipment is unbeatable despite the pops and other noises and the interviewer listened and had a spiritual experience. Then listened to high end multi-channel, high-sampled, digital media on the SAME SYSTEM and could hear the difference.
“does that mean that live is somehow worse? Of course not.”
I dunno. Some of my biggest letdowns have been seeing bands I had previously enjoyed playing live. U2 in particular. Bono was a pompous ass.
OTOH the Pink Floyd concert was fun….I think. I don’t remember all that much.
U2 has always had underwhelming arena-sized shows, their small shows all got rave reviews (I missed the small venue shows, but did see them on their early U.S. arena tour. Pink Floyd always tried to make the best out of the arena volume and did create a lot of fun stuff at their shows. I somehow remember the Pink Floyd show where my roommate snuck a fifth of Jack Daniels into the arena… I must have not been drinking much at that point…
This was the 1987 Joshua Tree tour. It was in Oakland Arena so not a small venue right after Bono spray painted that statue in SF. His dumb response was to double down on his shitty behavior to claim it was ritgeous artistic expression. To make it all OK he brought out the statue’s artist and had him spray paint the stage backdrop.
Yeah whatever Bozo, tell it to the judge.
Floyd was also Oakland Arena; A Momentary Lapse of Reason. That was a fun show. Kinda hard to see the stage though through all the smoke and I’m not talking about any stagecraft.