7+ Speed Transmissions: Marketing Gimmick or True Benefits?

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Ford is debuting a 10 speed automatic in the Raptor.

What's your take?

I remember reading an interesting article by James May on the subject a few years ago:
A really primitive petrol engine will give maximum torque at one engine speed. As refinements were added, the torque spread across the speed range a bit.

First there were things like automatic ignition advance and retard, which previously was the job of a little lever on the steering wheel. Later, there was variable valve-timing. More recently, there has been the widespread adoption of fuel injection and computer-controlled ignition mapping. All these things have helped spread usable torque across the engine's speed range, to make the car more tractable.

Now we are in an era when motoring writers thrill us with descriptions such as ‘a torque plateau like a cross-section of Norfolk'.

So surely the number of gears we need should be going down. More usable, more flexible grunt should mean less need to muck about with pesky gear ratios. Yet the number of gears is going up.

http://www.topgear.com/uk/james-may/may-razors-2011

I would need to actually study it, but I start to wonder whether the added time required for a shift (even in a DSG it isn't instant) actually starts to make the car slower? If you have a 3,000rpm [or larger] window of torque (entirely possible with today's engines) but each subsequent gear only gives you 1,000rpm before shifting to the next, is it really beneficial? What's the point of having a wide powerband if it's not even used? You could probably drive a Dodge Viper for years without ever taking it out of 3rd gear and have a perfectly satisfactory motoring experience. (For a diesel that might only have around 1,000rpm of useful torque, I can somewhat understand)

If a CVT is basically "the end" to increases in the number of gear ratios, and they are almost universally loathed, why are engineers steadily approaching an asymptote of gears? I'm sure you can't feel individual shifts in a 10 speed automatic, but I would dare anyone to feel the shifts (shift) of a 2 speed powerglide.

Efficiency is universally improving, but I think that has less to do with gear ratio increases and more to do with better engines and better aerodynamics.

Despite my earlier Dodge Viper reference, 1 speed transmissions are probably too little (although they seem perfectly acceptable for electric cars for some reason, but I digress) and ten speeds are probably too many. So where is the sweet spot? For me somewhere around 5 or 6 gears seems just about perfect...

Thoughts?
 
I'm sure you can't feel individual shifts in a 10 speed automatic...
I drove an Audi A6 a couple weeks ago that had the 8-speed auto in it, and I could definitely feel the shifts. At first I was wondering why it was changing gears so much, then it dawned on me.
 
With super fast shift times, more is better for performance. You can intentionally narrow the powerband, gain more power, and not suffer any large downsides. On the road more gears lead to more flexibility. My car has a six speed and I can generally keep the revs below 2000 with the exception of 4th gear and 6th gear. The latter is simply because of the speed I'm traveling down highways. A seventh or eight gear would make sense.

For a manual car, you'd probably want to limit gear. I feel like six well tuned gears is a good amount. The Viper, even with all its torque, did drop out of the best part of the powerband at high speed with what was effectively a 5 speed transmission.
 
With extra gears, you could possibly have more flexibility in how the transmission is geared. With 7 or more gears, the transmission could easily be geared short down low for acceleration, but taller up top for fuel economy, and get away with not using the last two gears to reach top speed. For example, the 8 speed automatic in the Corvette reaches its ungoverned top speed in 6th. That said, there should be a limit to how many gears a car should have. I think 10 should be the max, and that even 8 or 9 should be plenty for most applications. Well, for automatics at least. I don't know what the logical limit should be for manuals outside of semis and the like. Maybe 8. We already have 7 speed manuals. Adding more and more gears is not the end all be all for fuel economy. There are other factors. I think 10 is the logical limit on automatics, and that 8 is plenty most of the time. Though I would like to see someone make a car with an 11 speed transmission, just to make a Spinal Tap joke.

Not so sure about electrics. I think single speeds have less drivetrain loss on electrics than a transmission with multiple ratios. Or something.
 
I've no particular objection to umpteen speeds as long as they work well.

Some reasoning:

The theory is that even with a wide torque band the engine is still at its most efficient - be that in terms of performance or actual fuel efficiency - across a certain range.

The longer you can keep the engine spinning at that speed, the better. A car might develop the same torque peak at 1500rpm as it does at 4000rpm, but under light loads it will still be burning less fuel at 1500rpm. So if you're just cruising along, it doesn't make sense to have a transmission changing up at 4000rpm if you can have it change at 2000rpm and drop back down to 1500rpm each time. Particularly if you've got all that torque down low negating the need to venture higher up the rev range.

What's more, if you have several ratios to choose from you shouldn't be stuck without the correct gear occasionally. My car is in possession of a five-speed gearbox with exceedingly long gearing and not much torque to exploit it. It's an extreme example, but there are times when second gear feels like you're thrashing it but third doesn't quite have the power I want. If it had one, two or even three intermediate gears, one of them would be just right.

The other thing to consider is that several of those gears could essentially be overdrives. You might have five to enable decent acceleration and the others can be called upon at higher velocities for better cruising economy, as required. I've driven several cars with seven and eight-speed transmissions and really they're quite impressive - some will happily settle into a nice low-revs 6th gear at as little as 30mph - without feeling like they're labouring - and some will cruise at 80mph at quite a bit less than 2000rpm, which is one of those theoretical rev limits above which engine friction harms economy exponentially. And if you decide to prod the gas just slightly at low cruising revs, you have one or two slightly lower ratios to choose from to dictate your acceleration. It can work quite well.

Finally, there's occasionally some trickery to ensure not only that the engine works at its most efficient, but that it avoids uncomfortable resonant frequencies as a result of clever emissions/performance tech or plain old lugging. If you have a nearby gear able to give you an extra 500rpm or something then that may be all that's needed to avoid such frequencies.

General thoughts:

In manuals, I'm happy to stick to relatively few speeds. Six is plenty, I'm happy enough with five and there's something pleasingly simple about cars with four speeds.

I have also driven a car with a three-speed auto. An old Jensen Interceptor, with its big Chrysler V8 and slushbox. It was quite endearing in the way it sort of slammed from first to second (enough to chirp the tyres at full noise) yet slushed the second-to-third change. I don't doubt it'd be a quicker, more usable performance car with two or three more ratios though.

As for CVT, it's theoretically the ideal solution. I honestly don't mind them - the mooing noise that most people who've never driven a CVT complain about is only really a problem if you spend your life driving flat out or commute up a massive hill each day. In regular driving I've found them to be incredibly smooth and as good as inaudible most of the time.
 
With extra gears, you could possibly have more flexibility in how the transmission is geared. With 7 or more gears, the transmission could easily be geared short down low for acceleration, but taller up top for fuel economy, and get away with not using the last two gears to reach top speed. .
Exactly. Anyone who has driven a Subaru or any other car with short gear ratios on the freeway know about lack of flexibility and wish for more gears even on the 6speed models.
 
The problem I have is this. Highways (apart from the autobahn) have fixed speed limits. A general range of 100-120km/h probably covers most restricted highways in the world. A highway also happens to be about the only time a car is in "cruise" mode. How many optimized overdrives do you need? For me, it seems a 20km/h window can easily be dealt with using one gear, a difference of probably 500rpm (checked with a calculator, this figure seems about right). The rest of the time the car will be either accelerating or decelerating constantly. Do you need 7 additional gears for this low speed operation?

Here is a dyno of the deliciously linear S65 V8 from the E92 M3.

evosport_e92m3_pulley_dyno-.jpg


From 3,000rpm to about 8,000rpm the torque is basically the same. Why do you need a crazy flexible transmission when you have an engine this beautifully flexible itself? Why work with only 1,000rpm when you have more than 5,000rpm of totally usable torque.

Exactly. Anyone who has driven a Subaru or any other car with short gear ratios on the freeway know about lack of flexibility and wish for more gears even on the 6speed models.

I don't think the Subaru in this case needs more gears, it just needs ratios more suited for it's street purpose, including a longer final drive ratio. This video is actually what prompted me creating this thread:



The ratios in that rally car are absurdly short and the RPM's are falling by maybe 500 in each subsequent gear, which makes no sense because a peripheral port 20b makes a very similar torque curve to that BMW V8 posted above. Mazda, I think, realized this with it's factory race transmissions that have quite long gearing, an oddity in motorsports, but they are effective:



For the case of the manual transmission, let the flexibility of the engine do the work and you concentrate on driving the car.
 
From 3,000rpm to about 8,000rpm the torque is basically the same. Why do you need a crazy flexible transmission when you have an engine this beautifully flexible itself? Why work with only 1,000rpm when you have more than 5,000rpm of totally usable torque.

Because you'd still get optimum acceleration spending as much time as possible in the top 1200rpm, and optimum efficiency keeping the revs as low as possible without lugging the motor. It seems like this is very far from the first time I've said this but horsepower is God, torque can always be created through gearing so long as it's a non-zero number.

There's never a downside to having more ratios available outside of complexity. CVTs would be perfect, except they lack torque holding ability as well as the total ratio spread being narrower than ideal (you either lose out on low-speed torque multiplication or lose out on getting stuck with too high of revs on the highway), which is what has lead to the constantly-increasing gear count of modern automatics. I see nothing but potential greatness from a 9 or 10 speed automatic in terms of usability and performance as long as it can dump multiple cogs almost instantaneously based on throttle position.
 
Thought about looking at this from a historical point of view. This is American centric and only looking at automatics:

Timeline:
1950: Powerglide Transmission first offered. 2 speeds, low and direct (1:1) drive.
1956: Interstate highway act. 41,000 miles of highway begin construction
1964: Turbo Hydra-Matic transmission first offered. 3 speeds. 3rd is still 1:1
1973: Oil Crisis
1979: North-South Highway sections completed
1980: Ford AOD (Overdrive) transmission introduced
1981: GM THM-2004R (Overdrive) transmission introduced
1986: East-West Highway sections completed
1992: Interstate highway completed
2000: GM 5L40 5 speed transmission introduced
2007: GM 6L45 6 speed transmission introduced
2014: GM 8L90 8 speed transmission introduced
2017: Ford/GM 10 speed automatic introduced

So we went from 1950 to 1964 (14 years) to gain one ratio, and then another 16 years to gain one more, and then another 20 years to gain another. 50 years to go from 2 speeds to 5 speeds. But since then we've doubled it! Just seems crazy.

There's never a downside to having more ratios available outside of complexity. CVTs would be perfect, except they lack torque holding ability as well as the total ratio spread being narrower than ideal (you either lose out on low-speed torque multiplication or lose out on getting stuck with too high of revs on the highway), which is what has lead to the constantly-increasing gear count of modern automatics. I see nothing but potential greatness from a 9 or 10 speed automatic in terms of usability and performance as long as it can dump multiple cogs almost instantaneously based on throttle position.

I suppose it's the complexity that troubles me. Imagine how many moving parts a 10 speed auto has. I wonder how much they will cost to rebuild?
 
I don't think the Subaru in this case needs more gears, it just needs ratios more suited for it's street purpose, including a longer final drive ratio. This video is actually what prompted me creating this thread:
But if it had more streetable ratios it would lose its acceleration, The ideal would be to keep the short gears for acceleration and have a few more overdrive gears for highway driving. I would assume you have never been around Large trucks (Semis and other Medium to heavy duty trucks) they have a large number of gears to keep the engine in the optimum RPM no matter what the condition (large load or steep hills). Even with a gas engine like the BMW that has a broad flat torque curve could benefit from more gears since it would keep it in the most efficient portion of the rev band.
 
Large trucks (Semis and other Medium to heavy duty trucks) they have a large number of gears to keep the engine in the optimum RPM no matter what the condition (large load or steep hills).
Yes. Usually 12, 14 or 16 here. But the auto shift pattern changes a lot with load. So for 40t it would go 2, 4, 6, 8, 9, 10 etc. If the truck had no trailer it would go something like 4, 7, 10, 12. And for steep hills and overweight loads it would be straight through all of them, 1, 2, 3, 4, 5 etc. But always cruising at 50 mph in top gear, usually at the lower end (1100 or so) of peak torque, which is from 1000 to 1500rpm.

Full size manual trucks have range splitters, so under unloaded or light load conditions they would remain 6 or 8 speed. So 2, 4, 6, 8, 10, 12, 14, 16. Only using the other gears, 3, 5, 7, 9, 11, 13, 15 when needed.

Could we see this in cars? Something like a 10 speed auto but gears 2, 4, 6, 8, and 10 for everyday driving and the shorter 1, 3, 5, 7, and 9 ratios for performance/track driving. Or using all 10 for economy driving as the engine would be kept at optimum speed for as much time as possible, but being a short ratio 5 speed for the track at the drivers request.
 
But if it had more streetable ratios it would lose its acceleration, The ideal would be to keep the short gears for acceleration and have a few more overdrive gears for highway driving. I would assume you have never been around Large trucks (Semis and other Medium to heavy duty trucks) they have a large number of gears to keep the engine in the optimum RPM no matter what the condition (large load or steep hills). Even with a gas engine like the BMW that has a broad flat torque curve could benefit from more gears since it would keep it in the most efficient portion of the rev band.

I wouldn't want to shift 15 times to get to highway speed. Even if it was (somehow, despite the time required for shifts) faster.

There has to be a limit, even with fast autos, where the amount of time lost between shifts cancels out the advantage of better torque multiplication. At the same time, each additional gears adds marginal (if any real) benefit at the expense of complexity. Will we see 11 or 12 speed gearboxes? Ugh...I hope not.

Yes. Usually 12, 14 or 16 here. But the auto shift pattern changes a lot with load. So for 40t it would go 2, 4, 6, 8, 9, 10 etc. If the truck had no trailer it would go something like 4, 7, 10, 12. And for steep hills and overweight loads it would be straight through all of them, 1, 2, 3, 4, 5 etc. But always cruising at 50 mph in top gear, usually at the lower end (1100 or so) of peak torque, which is from 1000 to 1500rpm.

Full size manual trucks have range splitters, so under unloaded or light load conditions they would remain 6 or 8 speed. So 2, 4, 6, 8, 10, 12, 14, 16. Only using the other gears, 3, 5, 7, 9, 11, 13, 15 when needed.

Could we see this in cars? Something like a 10 speed auto but gears 2, 4, 6, 8, and 10 for everyday driving and the shorter 1, 3, 5, 7, and 9 ratios for performance/track driving. Or using all 10 for economy driving as the engine would be kept at optimum speed for as much time as possible, but being a short ratio 5 speed for the track at the drivers request.

I actually like this idea. A CVT could probably emulate something like that, but the CVT has other problems. It's effectively two 5-speed gearboxes in one transmission. To me, that is the best solution. I actually was not aware of that system already in place in trucks. I assume its a robot-box automated manual?

Relevant:
 
Yes. Usually 12, 14 or 16 here. But the auto shift pattern changes a lot with load. So for 40t it would go 2, 4, 6, 8, 9, 10 etc. If the truck had no trailer it would go something like 4, 7, 10, 12. And for steep hills and overweight loads it would be straight through all of them, 1, 2, 3, 4, 5 etc. But always cruising at 50 mph in top gear, usually at the lower end (1100 or so) of peak torque, which is from 1000 to 1500rpm.

Full size manual trucks have range splitters, so under unloaded or light load conditions they would remain 6 or 8 speed. So 2, 4, 6, 8, 10, 12, 14, 16. Only using the other gears, 3, 5, 7, 9, 11, 13, 15 when needed.

Could we see this in cars? Something like a 10 speed auto but gears 2, 4, 6, 8, and 10 for everyday driving and the shorter 1, 3, 5, 7, and 9 ratios for performance/track driving. Or using all 10 for economy driving as the engine would be kept at optimum speed for as much time as possible, but being a short ratio 5 speed for the track at the drivers request.


Its possible there is a aftermarket unit for cars and light trucks that does sort of the same thing in this case adding a over or underdrive to an existing transmissions gears.
https://www.gearvendors.com/
 
Ford's 10-speed is a ten speed because they included another shiftable element. With a transverse gearbox, you're not going to really want to go over 4 gear seats for packaging purposes. ZF's 8-speed is an eight speed because their goal was to make a transmission with the least amount of parts possible. Their 8-speed is the optimum between efficiency and simplicity, and the configuration they went with allowed them to directly replace the 6HP. That's two more gears with greater efficiency while retaining the same size and weight.

Ford's new 10-speed is even more efficient, but that's because they started from a clean sheet. They also nested some elements to save space.

As far as shift perception goes, the important thing about the 8HP, GM's 8L90, and this new 10R is that they all only have to simultaneously open and close one element for each shift.
 
Ford's 10-speed is a ten speed because they included another shiftable element. With a transverse gearbox, you're not going to really want to go over 4 gear seats for packaging purposes. ZF's 8-speed is an eight speed because their goal was to make a transmission with the least amount of parts possible. Their 8-speed is the optimum between efficiency and simplicity, and the configuration they went with allowed them to directly replace the 6HP. That's two more gears with greater efficiency while retaining the same size and weight.

Ford's new 10-speed is even more efficient, but that's because they started from a clean sheet. They also nested some elements to save space.

As far as shift perception goes, the important thing about the 8HP, GM's 8L90, and this new 10R is that they all only have to simultaneously open and close one element for each shift.
Since when did you switch from bio to mechanical engineering? Or did you just pull this out of your ass?
The problem I have is this. Highways (apart from the autobahn) have fixed speed limits. A general range of 100-120km/h probably covers most restricted highways in the world. A highway also happens to be about the only time a car is in "cruise" mode. How many optimized overdrives do you need? For me, it seems a 20km/h window can easily be dealt with using one gear, a difference of probably 500rpm (checked with a calculator, this figure seems about right). The rest of the time the car will be either accelerating or decelerating constantly. Do you need 7 additional gears for this low speed operation?

Here is a dyno of the deliciously linear S65 V8 from the E92 M3.

evosport_e92m3_pulley_dyno-.jpg


From 3,000rpm to about 8,000rpm the torque is basically the same. Why do you need a crazy flexible transmission when you have an engine this beautifully flexible itself? Why work with only 1,000rpm when you have more than 5,000rpm of totally usable torque.



I don't think the Subaru in this case needs more gears, it just needs ratios more suited for it's street purpose, including a longer final drive ratio. This video is actually what prompted me creating this thread:



The ratios in that rally car are absurdly short and the RPM's are falling by maybe 500 in each subsequent gear, which makes no sense because a peripheral port 20b makes a very similar torque curve to that BMW V8 posted above. Mazda, I think, realized this with it's factory race transmissions that have quite long gearing, an oddity in motorsports, but they are effective:



For the case of the manual transmission, let the flexibility of the engine do the work and you concentrate on driving the car.

Nah man, you're not factoring in the final drive ratio. Or the fact that peripheral port rotaries don't have flat torque bands, they have very high rpm torque peaks and thin torque bands.

It's obvious that the final drive in the Peugeot is very low because the car gains massive speed in between quick gear changes. Conversely, the RX7 seems to have a high final drive because it doesn't gain that much speed between seemingly long gears. The RX7 in the video doesn't seem much different than mine and is about as quick. It's probably a stock transmission.

My RX7 has long gears and a high final drive - 4.10 to be exact. Aftermarket companies make close-ratio gearsets for the transmission but the only way to increase the final drive without customization is to get a stock part which takes it to 4.30. Anyway, numbers aside, the only reason they gave the car longer gears than usual was for highway gas mileage and therefore emissions purposes. Even with a 5th gear made for 190+ mph it still only manages 25 on the highway.
 
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I've been interested in transmissions since the day my hyundai's transmission got stuck in 3rd. Driving home at 5k RPMs is pretty neat. Why was it that everyone was raving about the ZF 8HP when the transmission in my car was such a piece of crap?



So I watched the above video and read the patent papers for Ford's 10R and to this day keep all the information in my ass until the time comes when people are talking transmissions.

See the table at 0:40 in the video? The Ford is the right-most yellow box. ZF labels that configuration as checked and usable, but probably didn't use it because they didn't want to deal with the length or perhaps did not consider nesting elements like Ford did. The blue boxes are not usable because the gear ratios probably don't work well together.

This article goes over all the nerdy parts from the patent diagrams and puts it together for us:

http://www.thetruthaboutcars.com/2014/12/saturation-dive-ford-10-speed-transmission-power-flow/

Really great article there.
 
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Nah man, you're not factoring in the final drive ratio. Or the fact that peripheral port rotaries don't have flat torque bands, they have very high rpm torque peaks and thin torque bands.

It's obvious that the final drive in the Peugeot is very low because the car gains massive speed in between quick gear changes. Conversely, the RX7 seems to have a high final drive because it doesn't gain that much speed between seemingly long gears. The RX7 in the video doesn't seem much different than mine and is about as quick. It's probably a stock transmission.

My RX7 has long gears and a high final drive - 4.10 to be exact. Aftermarket companies make close-ratio gearsets for the transmission but the only way to increase the final drive without customization is to get a stock part which takes it to 4.30. Anyway, numbers aside, the only reason they gave the car longer gears than usual was for highway gas mileage and therefore emissions purposes. Even with a 5th gear made for 190+ mph it still only manages 25 on the highway.

Logan475vsold475.jpg


That's a peripheral port 20b. 225lbs*ft at 3500rpm and around 280 @ 8600rpm and 240 @ 10,000+. That is a *very* wide torque band. It's not a lot of torque, but its available all over the rev range. (The blip in the middle, IIRC is from a wonky intake setup, this is the Defined FD)

Here is a 13b-pp
dyno1.jpg

Little narrower, but 4250-9,000 is still pretty damn wide. And 4250 is just where they started the dyno run. Peripheral port engines are monsters....

The RX (RX3 actually) in the video I posted uses a Mazda racing gearbox (notice the weird shift from first to second). My 7 also has 4.10 gears in the rear end from the factory, not sure I understand your point.. And your RX7 (unless you have significantly upgraded it from last I saw) is nowhere near as fast as that RX-3. Notice how it blows by a rally-prepped Celica at 130mph at the end. That's likely a 300whp 13b.

Here's another RX, an IPRA prepped RX-7, with fairly long gearing:


Seems to have no problem running/out running the V8's. Not bad for an all motor 1300cc.
 
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I feel like that's whats next. Especially for a manual gearbox, it makes sense. Of course new versions would be all push button activation.

Just found this article from an interview with head of ZF world and ZF NA

Now, Automotive News Europe (subscription required) quotes ZF CEO Stefan Sommer as saying nine speeds are the “natural limit.” In Sommer’s words, “There is no hard line, but you have to consider the law of diminishing returns. The question is whether adding even more gears makes sense.”

That sentiment is echoed by Julio Caspari, president of ZF’s North American division, who believes that the race for more gears is driven by marketing and not engineering. As proof, Caspari says that there’s only an 11-percent gap in efficiency between today’s most-efficient gearboxes and a theoretically perfect ideal.

We’d be the first to point out that more gears equal more complexity, higher cost and, potentially, more points of failure. Unless someone can conclusively prove that ten speeds are better than nine, we say let’s turn our attention to other areas, like making more power from less displacement.

http://www.motorauthority.com/news/1080293_zf-ceo-says-nine-speeds-are-the-natural-limit

Also, can't forget the infamous Corvette 4 +3 trans...
 
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I actually like this idea. A CVT could probably emulate something like that, but the CVT has other problems. It's effectively two 5-speed gearboxes in one transmission. To me, that is the best solution. I actually was not aware of that system already in place in trucks. I assume its a robot-box automated manual?
Yes, robotised manual, Volvo's I-Shift for example. Although heavy haulage trucks (for well over 100t) use more familiar torque converters. Full manuals (with up to 16 speeds - 8x2) are still available and are more efficient than autos if driven well.

Having a 10 speed auto in a car with the ability to lock out the 'high range' gears could be useful.
 
The problem I have is this. Highways (apart from the autobahn) have fixed speed limits. A general range of 100-120km/h probably covers most restricted highways in the world. A highway also happens to be about the only time a car is in "cruise" mode. How many optimized overdrives do you need? For me, it seems a 20km/h window can easily be dealt with using one gear, a difference of probably 500rpm (checked with a calculator, this figure seems about right). The rest of the time the car will be either accelerating or decelerating constantly. Do you need 7 additional gears for this low speed operation?
Yes, for the reasons I mentioned above.

Your example also assumes that a car will either be cruising at a set speed or accelerating at lower ones. I know from having done a couple of long road trips in the States that in some ways, you could happily get on with a car that has four short acceleration gears and then a ludicrously long overdrive, because you can feasibly travel for hundreds of miles at 70mph without ever needing to slow down... and when you do slow down, it's likely to be when you hit a town and the lower gears are perfectly adequate.

What that doesn't cover is a country like, for example, the UK - where motorway speeds can (and do) vary between 5mph and 90mph on a regular basis as traffic ebbs and flows. This means rather too much accelerating and decelerating rather than nice bouts of cruising along at a constant speed.

You also mention, and dismiss, the Autobahn. While it's a fringe example, that doesn't mean it isn't relevant - if a 9 or 10-speed transmission works best for a country where speeds are unrestricted on some roads, then they'll design it for that country. It doesn't make sense to sell one transmission in one market and one transmission in another.
From 3,000rpm to about 8,000rpm the torque is basically the same. Why do you need a crazy flexible transmission when you have an engine this beautifully flexible itself? Why work with only 1,000rpm when you have more than 5,000rpm of totally usable torque.
Again, I explained this in the post almost immediately above yours. Whether the engine is flexible or not, it's still operating at peak efficiency over a much smaller band than a wide torque peak suggests.

Consider a car driving in a really mountainous area. Obviously you want plenty of power to climb hills, and that means using more fuel to negotiate the slopes.

Let's say a six-speed auto transmission corresponds to maybe 2500rpm at 70mph up a hill. You've got a nice torquey modern turbocharged motor under the bonnet, deveoping its peak torque from 1500rpm all the way to 5000rpm. So your car is perfectly happy doing that 2500rpm, and you're not having to change down.

But an eight-speed could be doing 2000rpm, and still happily sitting at 70mph, using less fuel.

Now let's say the hill gets steeper. Your six-speeder changes down to 5th to ensure you can still cruise at 70mph. The jump might be the same as the eight-speeder going from 8th to 6th... but instead the eight-speeder only needs to drop one gear, because the intermediate ratio has enough power to keep you rolling up the hill but dropping that intermediate ratio enables it to maintain some semblance of better fuel efficiency.

And if you really booted it on the steep hill, the 8-speed 'box is more likely to drop to a gear at which usable acceleration is available - whatever gears it subsequently changes up to are more closely spaced around the optimal engine speed.

Now as the Motor Authority article says, there's probably a natural limit - a point where internal friction or simply weight mean you're fighting diminishing returns. But at the moment, that's not the case - several cars going from 6-speeds to 8-speeds for example (brands that use ZFs like Jaguar and BMW) are undoubtedly getting more economical and more driveable as a result. I've driven several cars with ZF's 8-speed and it's a fantastic transmission - smooth, quick, and - surprise surprise - is rather good at choosing the right gear for the right moment.
Having a 10 speed auto in a car with the ability to lock out the 'high range' gears could be useful.
When you say 'lock out' do you mean prevent them from being used? Or are you talking about torque converter lock-up where transmission and engine speeds rise in unison?
 
When you say 'lock out' do you mean prevent them from being used? Or are you talking about torque converter lock-up where transmission and engine speeds rise in unison?
Yes prevent ratios from being used. I think this already happens in VW's DSG 'boxes. In Sport, 7th doesn't get used.
 
Yes prevent ratios from being used. I think this already happens in VW's DSG 'boxes. In Sport, 7th doesn't get used.
Okay, that makes sense. I find VW's Sport mode of limited use in the DSG cars, unless you really are driving quickly. If you just want to hack along at brisk pace, but not properly fast, it hangs onto gears for way too long. Maybe it's just me that would knock it into manual mode if I wanted to actually drive in a 'sporty' manner!
 
Particularly in diesels, S mode is not of much use as the rpm gets too high for a brisk pace. All of VW's DSG 'boxes come with a manual mode anyway, some with paddles on the wheel.
 
A gimmicky way to help increase fuel economy by avoiding the higher RPMs. 👎


Jerome
 
How is it a gimmick to increase efficiency?

It's a car that will be shifting constantly, which means more wear and tear so the efficiency may come at a cost later on down the road.

Jerome
 
It's a car that will be shifting constantly, which means more wear and tear so the efficiency may come at a cost later on down the road.

Jerome

That's not a very good argument, you could say the same thing about how there is less stress on the engine due to a larger selection of gears.
 
It's a car that will be shifting constantly, which means more wear and tear so the efficiency may come at a cost later on down the road.
To play devil's advocate, how do you know it won't have less wear and tear than a gearbox with fewer speeds - given it spends less time in any one gear?...
 
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