7 SPEED AUTO versus 5 SPEED AUTO

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Many of the new models feature the 7 speed. Does this transmission provide significant performance and economy advantages over the 5 speed?
I know that the 7 speed is not on the higher horsepower
higher cost models because it cannot handle that much power yet - it just seems odd that the most superior transmission is not available on the best models.
.
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From reading other forums, E500 buyers who have the 7 speed rave about it and have claimed both performance and gas milage increase over the 5 speed.

You may have this backwards. The E500 has the 7 speed, the E320 does not. The reason being the torque( I think) as being lacking in the E320. The CLS 350 will have the 7 speed as standard (as will the CLS500) and I imagine when the E gets the new V6 350, it also will have the 7 speed. I am sure the new S will have the 7 speed. I think the 7 speed will be installed as the engines measure up to performing with it.

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I may have it backwards and forwards ( the best of all worlds ).
I was thinking of the SL500 compared to the SL55 and SL600.
.
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The question is, too, whether you are comparing to....
or
with...
DAS
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The more gears you have...the better fuel economy can be provided and better acceleration along with the flexibility.
I thought 5 speeds auto was awesome... can't imaging what a 7 speeds will do.
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better
The problem with adding more gears is that it adds more parts with more potential for failure. Personally, I like CVT. It's simple, and the modern implementations (i.e. Audi and Nissan) have been very trouble-free.
--

- RODNEY



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That's true too...I don't think it is that much more parts, though. Electronic world.
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Seven speeds....??? I'm so used to that three speed w/ kick-down switch that I wouldn't know how to act! (then again, I still dip when I dance. ..)
Jerry wolfram '78 450 SL - 212K miles
Tiger wrote:

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I also think the CVT is a superior engineering concept. However, it doesn't mean it is more desirable in use. Apparently the CVT feels weird to drive. Due to the behaviour of the motor in response (or lack of), there is an absence of the usual visceral cues when the driver accelerates.
In a sense, it may lack the rush of a downshift. Depends on one's driving preferences I suppose.
Michael
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MY wife's Audi A6 has a CVT. It actually is very fun to drive with very little weirdness. In casual driving, there are no shifts and the engine always just seems to be "idling" along, but always ready to throw in a boost of power if needed. When you do decide that you need that boost, all you have to do is floor it and it still gives you that "kick-down" response - the engine goes immediately to a few hundred RPM below redline and the transmission instantly "gears" down. If you continue to leave the accelerator on the floor, the engine stays at near redline, but the transmission continues to "gear" up, increasing road speed. This may feel a little weird, but when you are on the highway and need to pass, it's amazing. The car goes from 70 to 90mph in no time at all. It's all computer programmed to maximize torque and horsepower for the given demand.
Of course it also has the Tiptronic mode, which give you six pre-set "gear" points. The engine will actually go to redline and then upshift, just like a standard transmission. It will also downshift if you floor the accelerator and will downshift as you slow to a stop. All shifts are made with no loss of torque since the band is always in contact and driving the pulleys. The only really weird thing that took some getting used to is that the car uses an actually viscous controlled clutch instead of a torque converted. It engages when you let your foot off the brake. Because of this, there is the perception of hesitation when accelerating from a stop, but its actually about the same as if you were manipulating a clutch on a manual transmission.
Overall, I like the CVT. I only wish that it had been available in AWD, but apparently, there are some engineering concerns with that. We actually set out to buy the AWD version, but we could never find one in the right color (remembers, this is my wife's car). Also, after driving the AWD and CVT versions, we decided we liked the extra performance of the CVT. Besides, we really don't need AWD since we also have an M-Class for those rare snowfalls.
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<snip>
Thanks for the personal notes. That was very informative to read.
I understand the CVT Audi can be a very satisfying car for many people. From what I've read elsewhere the CVT can make for a pleasant and predictable drive except in two "weird" situations - one of which you've noted being the way the car behaves as it gathers road speed under constant engine speed - not unpleasant but just different. The other is when you tip-in or lift off the brake from stop or on a slippery surface. Apparently, there's not much control for the driver and the car tends to lurch forward. It would be better if the CVT could allow feathering the tip-in.
I guess I'm old-fashioned but I also find it very useful to keep the engine revving at a certain RPM (not red-line) while maintaining relatively low vehicle speeds. I don't think the CVT would be the ideal platform for that. I understand Audi has a "double-clutch" version of the SMG transmission in the works. Maybe it will be smoother than the BMW's in city driving.
Michael
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It's not as easy or intuitive as with a conventional transmission, but it can be done by modulating the brake pedal. Regardless, it is annoyance in certain situations. One good thing is that once it "stabilizes", the car is able to hold itself perfectly still on the steepest of inclines without a foot on the brake or accelerator.
One other note I will add is that I have driven a turbocharged 1.8 A4 with the CVT and it seems to be a much better marriage than the 3.0 in the A6. The fact that there is some turbo lag really helps starting off in the CVT not seem so "aggressive". The 3.0 is very powerful at low RPM's and it exacerbates the stop-to-start problems with the CVT. Also, I have to admit that I hate the Tiptronic system. I much prefer the MBZ's Touchshift. With Tip, you have to move the shifter to another part of the gate and then the motion is forward and backward. With Touchshift, it's always ready to shift by giving it a gentle left or right nudge.
--

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Wasn't CVT initially developed for small engines, anyway?
DAS
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Yes, but because of limitations of the CVTs, not of the engines (problems to handle high torque). -------------------------------------------------------------------
Dori A Schmetterling wrote:

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The original CVT's used a belt that was not capable of handling high torque. Modern implementations, such as those in the Audi's, Nissan Murano, and Saturn VUE, use a metal chain that is capable of handling as much torque as any commercial engine can output.
--

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I tried one a few weeks ago and was very impressed. It was very smooth and there was almost no perceivable hesitation between shifts. The engine could still be enjoyed as the transmission still shifted up and down and would rev the engine across a range. As some testers have noticed, it almost makes going fast too easy.
Michael
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From what I've heard, the 7 speed gearbox is capable to make a downshift over two gears at once, while a 5 speed gearbox can only do a downshift by one gear at a time. So downshifts by several gears can take a little bit longer with a 5 speed than with a 7 speed.
This shift speed advantage may not be necessary with cars with really big engines, as they have enough power to handle almost any driving situation with a one gear downshift. Shifting down further (with full throttle) may only wake up the traction control, if you have 500 HP under the bonnet;-)
Frank
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greek_philosophizer wrote:

An MB press text about them on my site at http://www.mbspy.com/7g.htm
Main advantages featured by MB are Fuel saving of up to 0.6 litres per 100 kilometres Even shorter acceleration times and quicker intermediate sprints
Line 1 for us Europeans, line 2 for you Americans ;-))))
Juergen
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Ain't that the truth!!!! Guys on the W211 MB World Forum can't wait for the new bigger V8 and always are asking about flashing the ECU for some more juice.
Wait until some emergency kicks the price of gas to over $3-4 a gallon and you will see them looking for a diesel or is there a flash to shut down 2 cylinders...:-)
Jack
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Nevada Jack wrote:

They miss the point: Having fun with their cars as they are.
The chase for ever-more power in the last consequence does not lead to anything as it is totally unimportant if a normal road car has 250 or 265 hp.
Some time ago I read an article regarding photography and equipment about the _chase for the magic bullet_ <http://www.largeformatphotography.info/chasing-magic-bullet.html which describes the same problem as with cars and more power: The limiting factor is the user/driver.

< $3-4 a gallon and

I think there is a lot of truth in that - a friend just told me that in the countryside of North Carolina some neighbours recently sold their old V8 SUVs due to increased fuel prices and now drive smaller vehicles with smaller engines.

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