mind boggeling presumption? (manual more efficient than automatic?)

[niky]

Originally Posted by dmafanp

Some of the new vehicles have automatic trannys that surpass manual in the epa.

I read this and was ready to jump in, but MetroMPG explained it all already.

To note: I've driven hundreds of new cars over the past few years, and have been able to get week-long tests in both manual and automatic variants of a dozen odd of them.

It isn't even close. Unless the automatic is a CVT, the manual will always outdo the automatic in every situation.

CVTs can be driven to economy numbers as good as manuals given certain conditions, but this is highly dependent on the CVT in question. The Honda CVT from the first-generation Insight and first-generation Fits (from outside America) seem to do very well, as does the Mirage CVT... but as MetroMPG showed, in real life, manual variants of the Mirage still do better (especially in traffic, where the extra losses of the CVT are still noticeable).

[P-hack]

That is key, any kind of transmission can be automated, even a manual with some servos(probably wouldn't even need synchros). What is needed is an efficient transmission of energy to the wheels. CVTs have some inherent losses in them, as do automatics (plus costs). This needs to be weighed against the operating efficiency parameters of the engine/motor, and I don't know of many/any cases where cvt would come out ahead.

If you want to automate acceleration for best efficiency, you basically replace the gas pedal with a footswitch, it simply becomes a command for "accelerate at best efficiency", and hopefully it freewheels when not accelerating. I think this is very doable, today. But "power" and "performance" still sells cars too...

Just a caveat about extreme automation, will it allow some measure of "civil disobedience" when the situation calls for it, either to exceed the speed limit on a pulse for even greater efficiency, or in an "emergency"?

[tony_2018]

Of course a manual speed transmission is better because it its not using fluids to make the gears turn and thats where the automatics lose out. Also not everyone can or wants to drive a manual transmission. Also Honda is now coming out with a dual clutch transmission that still utilizes a torque converter, interesting design.

[user removed]

I can feel my dual clutch 6 speed powershift in the Fiesta downshifting when I am coasting in neutral. I wonder if it even has a neutral or if it just keeps the clutches disengaged.

regards
Mech

[Fat Charlie]

Car companies are very good at designing and manufacturing things. They can build wonderful slushboxes that excel at being operated for the EPA testing. I don't work as an EPA test driver, so I use EPA ratings the same way I use 0-60 times: as a largely irrelevant number that only serves to give an idea of relative performance to other cars being operated exactly the same way under identical circumstances.

In real life if you can and care enough to do more than simply shift into Dumb, there's no comparing the two. An auto doesn't know what's going on outside the car or what you're trying to do.

[Xist]

Metro, thank you very much for sharing that information! I have seen several discussions on here regarding the superiority of modern automatic transmissions, but it is great to have numbers showing that people get better mileage with manuals in the real world!

Old Mech, that kind of sounds like the high-mileage competition with astronomical MPG calculations, where college kids drive motorized enclosed recumbent bikes. I do not intend to disrespect the research, hard work, and achievement there, but until we have entire cars weighing less than single components in our current ones, not to mention impossible aerodynamics, and unrealistically-slow speeds, it does not seem relevant.

A few weeks ago for my Energy in the Global Arena class, we were required to attend a lecture by Amory Lovins. He talked a lot, that was the point, but he discussed using modern fabricating techniques to craft car bodies straight out of carbon, and raved about how much energy it took, how much lighter the product was, and how much less energy it required to power it. It is exciting to think that projects like CarBEN could be far simpler.

[deejaaa]

Originally Posted by dmafanp

This is great I would love to take a smash and go driver using both manual an auto and compare te differences in real world scenarios clearly the manual would win but I want numbers thanks

5 speed 2002 Jetta TDI, 61 mpg.

[serialk11r]

Originally Posted by tony_2018

Also Honda is now coming out with a dual clutch transmission that still utilizes a torque converter, interesting design.

Kind of silly IMO since normal autos shift fast enough (100ms vs 50ms, big difference...) but it would be good for reliability. The clutch change on a dual clutch auto is probably horrendously expensive, and the clutch fluid is not something that you can leave in there for 100k miles and have your car still function, whereas a torque converter auto can be abused like that.

I drove a new 981 PDK Porsche Cayman and I was kind of excited to see how it would do when I saw the brochures talking about auto-coast. Well, it's basically no better than the automatic in any other car, though it shifts a hair faster when you press the "+" button and the auto blips are certainly better than the crappy cars that just select a lower gear and then use the clutch to drag the engine up to speed. The auto coast is totally useless because the computer sucks at deciding when to coast, and the shifting pattern is exactly like any other car in auto mode.

Oh and on top of that, not having a clutch and gear shifter is incredibly boring once you're used to having it. I'll take my manual transmission with less gears and slower acceleration any day. With the 7 speed manuals coming out, I'm definitely not concerned about getting "less" fuel economy, and besides you don't have to lug around the solenoids and extra clutches, which saves ~2% curb weight.

[niky]

Dual clutch clutch packs cost something like two to three times as much as a regular clutch. And that's considering you can replace them. Early dual clutches claimed "lifetime" use... which meant that if you burned the clutch packs, you had to replace the entire transmission.

A dual clutch with a torque converter would be nice, but as you said... that extra-fast shift doesn't really matter all that much, in the grand scheme of things. I still like the Mazda torque converter automatic better than 99% of the dual clutches I've ever driven.

The Toyota-Lexus planetary gear system is better yet, but probably not applicable without hybrid assist.

[digital rules]

Originally Posted by Old Mechanic

My Fiesta's automated manual transmission is one pathway to the future of shiftless driving

Is this similar to a DSG tranny? The DSG seems to be a great transmission, but I am assuming it is not seen in more car's because of cost. Not sure if it has any other downsides either?