interesting trend? Slush boxes getting better MPG's?

[MechEngVT]

Originally Posted by ttoyoda

I wonder if the emissions test are done with the EPA drive cycle. If not, lean burn and to hades with the NOX here we come

I think they are. I read somewhere that they don't measure fuel used, just a full analysis on all collected emissions during the drive cycle and calculate fuel used from carbon emissions. This averages the concentrations of pollutants over the cycle since 2-stage catalysts alternate between high NOx and high HC/CO ppms during operation.

I just can't remember if that was the EPA or EU test...

[ttoyoda]

It's just the shear amount of automatics bought new.

And what about the tension load of automatics? Not to mention Poisson's Ratio?

[garys_1k]

Originally Posted by ttoyoda

Exactly right. The bosses bosses boss comes down to engineering and declares "mileage must improve, I don't care how you do it". Now we know EXACTLY what the EPA mileage cycle will consist of. EXACTLY. We could build an ECU that recognized the EPA test if we wanted to, and hypermile the engine when we detect an EPA test is being run. Piece of cake.
I wonder if the emissions test are done with the EPA drive cycle. If not, lean burn and to hades with the NOX here we come

Nope, no can do. While "detecting" running the EPA trace is possible, such would constitute a "defeat device" and result in big, big fines. Fuel strategies are built around the types of speeds and loads the cycles use, but not the cycles themselves.

For example, car makers enrich the AFR at high loads to get more power (or protect the catalyst from overheating) but that is done with full disclosure to the EPA.

BTW, fuel economy is measured DURING the emissions tests -- they're not separate tests. Atoms of carbon are counted and the FE is ascertained by how much passes out the tail pipe.

[garys_1k]

The next trend in autoshifting, already in use in Europe (e.g. Volkswagen) are dual shaft, dual clutch automatics. One shaft for odd gears, another for even. Engage both first and second gear at the same time, then engage the odd shaft clutch to pull away. When it's time to upshift, let out the odd shaft clutch and bring in the even. While second gear is in use and the odd shaft's clutch is open, shift to third for the next shift. Continue on up to top gear.

If wet clutches are used the only penalty is the oil pump. If dry clutches are used you have identical losses (small) to a manual trans, over 95% efficiency. Give the driver shift paddles if he wants to be in charge, but override for engine overspeed.

[RH77]

Originally Posted by ttoyoda

And what about the tension load of automatics? Not to mention Poisson's Ratio?

Funny, wiseguy

You misspell one adverb around here...

RH77

[jonr]

Do skilled eco drivers find that it is easier to exceed epa estimates with a manual?

I don't doubt that an auto transmission can out drive an average driver.

[Bror Jace]

jonr, I believe that's the conventional wisdom here. Manuals still rule for average fuel economy ... but I think they are gearing the automatics taller (lower number) for expressway use as they can downshift in cruise control while a standard/manual cannot.

[RH77]

Originally Posted by Bror Jace

... but I think they are gearing the automatics taller (lower number) for expressway use as they can downshift in cruise control while a standard/manual cannot.

That seems to be the aim lately. I would have to estimate that the switch has happened within the last 3-5 years.

Automakers have given up on selling manual transmissions to the mainstream public. To meet CAFE standards on the sum total sold, the automatic gearing has likely been adjusted to meet demands. Manual drivers either will pay less up-front for a "cheap" vehicle, or buy it for sport (and not care about FE anyways).

RH77

[metromizer]

Originally Posted by MechEngVT

...They let engine builders go for large hi-rpm horsepower without having to worry about bogging the engine (hi-stall converters) and shift much more quickly and consistently than a stick, maximizing time with power to the wheels and minimizing chances of breaking out or missing the time for bracket racers.

I have to wonder about autos with higher EPA ratings...does it translate to reality or is it because the PCMs are "gaming" the drive cycle? I still believe that it would be easier to get better mileage through altered driving habits out of a stick than a manual <I think you meant 'auto' instead of 'manual'?>

Apples-to-apples the manually shifted drag cars are always quicker, all things being equal (getting the car to hook, etc) but like you said, the PG slushbox cars are a lot more consistant, hands down (not to mention easier to cut an awesome consistant light using a trans brake w/dealy box). I've drag raced a 4-spd car for about 10 years I hate racing the automatic cars...

Having said that, I prefer and automatic in my commute car, but chose a manual for FE.

I have to wounder about the higher FE being shown for automatics, but I did just read a real good article about the newer breed of hybrid auto-manual boxes hitting the showrooms. Dual clutch, CVT, then refinements of lockup converters and the like, there is a lot of gray areas.

[MazdaMatt]

In the north american market, stick is not for economy, it is for sport. Mazda: Zoom Zoom. Buy a stick so you can highway cruise at 3500rpm and have power to pass without downshifting. I would love it if my mazda had another gear so i could highway cruise at 1200.