As we reported last month, it appears BMW and Audi, following the lead of Lexus, will begin to offer eight-speed automatic transmissions in their flagship models. Sources are now saying the transmission will be supplied by ZF Friedrichshafen, a familiar German supplier to both marques. Although we don't know all of the specifics, Audi is expected to debut the new slushbox in the range-topping A8 sedan, Q7 SUV, and their future A7 premium model. BMW will likely debut the new gearbox in their premium 7-Series sedan and the X6 Sport Activity Vehicle, according to company sources.
The current Audi A8 and BMW 7-Series both use six-speed automatics. The Mercedes-Benz S-Class utilizes a seven-speed automatic of their own design, while Lexus debuted their eight-speed transmission in the LS 460. Increasing the number of forward gears offers advantages in smoothness, acceleration, and improves fuel efficiency. Lower fuel consumption equates to reduced emissions, helping the powerful models meet increasingly stringent air quality standards in Europe and the United States.
[Source: Automotive News, subs. req'd]
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Reader Comments (Page 1 of 3)
Josiah @ May 12th 2008 3:02PM
Dumb question (I'm honestly ignorant on this topic; is there a point where adding "gears" becomes less effective (both performance and efficiency wise) then employing a CVT? Is that where we are headed?
Michael Harley @ May 12th 2008 3:14PM
Current CVTs may be torque limited...
Mark @ May 12th 2008 3:50PM
I'm not sure, but please use commas instead of parens.
Carlos @ May 12th 2008 3:39PM
Yes it does, and if companies would invest the amount of money it takes to develop a new gearbox into a CVT, it wouldn't take that long to develop one that isn't torque limited. There are applications using hydraulics that can be used but their weight is an issue and they aren't as efficient as using the belt system in current CVTs because of fluid losses in compressing the hydraulic fluids.
yacoub @ May 12th 2008 4:09PM
Yes, and there are several diminishing returns:
more gears in the same space = smaller gears = less durable. more gears = more shifting = increased wear on clutch packs and shift mechanisms. more gears = car is always shifting = unsettling driving experience for those used to a more normal amount of shifts. more gears = more shifting = higher transmission temps from more frequent activity = shorter lifespan or need for additional cooling capacity.
and the list goes on...
Johnny @ May 12th 2008 4:20PM
Thank god vacoub is not an engineer at an automaker anywhere. Or we be driving 1 speed automatics with his logic.
pmiddle5 @ May 12th 2008 4:31PM
^^^^why is that a bad thing? I still want a regular manual option though. Slower, heavier, ancient, I still want it
Disgruntled Goat @ May 12th 2008 5:01PM
If you look at the top fuel misers you'll see they all use CVTs or 4 to 5 speed boxes. I suspect the 8 speed auto is driven by the marketing guys, not the engineers.
Derek @ May 12th 2008 9:21PM
CVT's generally have higher drive line losses than conventional transmissions.
Pmiddle - manual transmissions are typically lighter than an automatic of equal gears. Manuals can be faster than their auto counterparts as well but it requires an experienced driver rather than just placing a brick on the gas.
Mal Fuller @ May 12th 2008 6:47PM
There's that old standby called the law of deminishing returns. Whatever happened to the KISS theory?
Joel @ May 12th 2008 7:03PM
@Johnny - He could also be implying diminishing or non-existent returns after so many gears.
yacoub @ May 13th 2008 11:10AM
@Johnny: Was clearly talking about the recent rise of 7+ gear transmissions. @__@
Seanross @ May 12th 2008 3:03PM
Nice, but won't Lexus come out with a 10-speed the year after then? You know how they wanna be "superior" and all...
unsure @ May 12th 2008 3:05PM
I'm just curius, but has anyone driven one of the Lexus' models with the 8-speed tranny? Does it feel like a normal transmission or can you tell a difference?
Eddie @ May 12th 2008 3:22PM
my friend has a gs460 with the 8 speed trans. it feels smoother than the 6 speed. the power comes very quickly and smoothly.
Amber @ May 12th 2008 3:46PM
We recently bought the ISF with the 8 speed auto. Its great. Very smooth and the power is always there. At 70mph it turns 2100 rpm on the hwy.
JD @ May 12th 2008 3:47PM
In Car and Driver's recent comparison of the M3 Sedan and IS-F, they said the 8 speed transmission was too much.
"...the eight ratios felt like too many, and in the twisties, we frequently found ourselves glancing at the gear indicator in the gauge cluster to discern which cog we were in."
Makes sense to me. 6 is really about all you need, I think- 4 close ratios for fun stuff, then gears 5 and 6 for long distance, high speed, low RPM cruising. 8? Really? I hope this pissing contest just ends soon. It's pointless. Just give us a 6 speed manual!
AM @ May 12th 2008 7:49PM
I own an LS-460 and after driving all of the German offerings I was convinced the 8 speed transmission was the best of the group. The people who say it "hunts" too much simply don't know how to get the best from the car. Depending on how you drive It engages 1 of 2 shift patterns. If you drive hard it will give you all the power when you ask for it (shifts alot). If however, you drive with a little more restrain, you will find yourself in a pleasant nirvana of holding high gears and only downshifting when you mean it to. It shifts in 160ms and that is plenty fast for me. P.S. I admit to its complete lack of steering feel.
Steve in TN @ May 12th 2008 3:06PM
I hope this BMW trans will be better than the one (a GM 5 sp. automatic built in France) in my 2000 3series which are to this day self-destructing anywhere greater than 40K miles. I hope ZF does a better job than the GM transmission unit.
IK47 @ May 12th 2008 3:25PM
of course, man
look at the ZF auto transmission in the 335i
fantastic auto
they only use the getrag ones in the lower models (328i?)
and I think even those ones have been improved