Last post on Feb 24, 2011 at 4:47 PM
You are in the Porsche Cayenne
What is this discussion about?
Porsche Cayenne, Car Buying, SUV
#20 of 29 Re: Just ordered manual tranny Cayenne [elias]
Jan 22, 2011 (7:07 am)
With a manual transmission how might the factory design engineers ascertain themselves that a FULL fuel cut during coastdown periods would not result in a COMPLETE engine stall and therefore use of the starter motor, or a clutch "dump" ("push" restart), upon the need to restart...?
With an automatic the factory engineer "is in control", with a manual it would require the driver to be cooperative with executing the incremental downshifting.
#21 of 29 manual vs. automatic
by kyfdx@Edmunds HOST
Jan 22, 2011 (7:26 am)
I think the zero-fuel on coasting is the least of the variables when comparing...
Manuals and automatics almost always have different final drive ratios... It's like comparing apples and oranges.. The application on different vehicles would be different... For instance, on my wife's car, the auto transmission will downshift when coasting down a long slope, requiring the driver to apply throttle to maintain the current speed... I can put my manual in 5th on the same hill, and coast with no throttle, maintaining speed.. That's just one example... I'm sure there are plenty of examples on the flip side..
Stating that one or the other will always result in higher real-world MPG is just a guess...
#22 of 29 Re: manual vs. automatic [kyfdx]
Jan 22, 2011 (9:50 am)
You're missing the point.
First, the presumption is that if you lift pressure completely from the gas pedal then you are doing so to enter coastdown mode, with an expectation that the vehicle will begin slowing. With an automatic transmission the designers then have the option of improving FE via full fuel cut and keeping the engine from stalling via incrementally downshifting the transmission as roadspeed declines.
"..requiring the driver to apply throttle to maintain the current speed.."
Not if the downslope is "enough".
Just as in your own example there is an equivalent speed, and down slope, wherein your wife's automatic will also coast downhill with no speed declination. The exception being if she should happen to step on the brakes, even ever so slightly. In that case the shift pattern switches to "help slow the vehicle" using engine compression braking, more aggressive downshifting, rather than a simple fuel cut coastdown.
"...Manuals and automatics almost always have different final drive ratios..."
Stuff of legend....
These days the only time the torque converter is in the drive "loop" is during acceleration, if the brakes are being used, applied, or the roadspeed is so low the lockup clutch MUST be disabled.
You may have noticed that while 6(10) speed automatics are now common, with 8(15) speed automatics not uncommon, manuals seem to be stuck at 6 speeds, passenger vehicles only.
How many of us would wish to "stir", CONSTANTLY stir, a manual transmission with 10 forward speeds, let alone 15, in order to keep the engine RPM at the most optimal(***) insofar as FE is concerned.
*** Lowest engine RPM, lowest frictional component, wherein the engine just barely produces enough "go" to maintain the current desired speed. CVT is IDEAL, otherwise the more gear ratios the better. But, to me, 8(15) (Lexus LS) does seem a bit beyond reason.
#23 of 29 Re: Just ordered manual tranny Cayenne [habitat1]
Feb 20, 2011 (5:12 pm)
We test drove a Cayenne (again) yesterday. The used car manager was not on-site to appraise our MDX so we had to wait until Monday. Just got an e-mail from the rep saying he can't order any more manuals during this model year. You can still spec one on the Porsche website...very disappointed.
I was wondering which dealer you ordered yours from?...I want to contact them. I will also call another dealer around here.
#24 of 29 Re: Just ordered manual tranny Cayenne [ledname]
Feb 22, 2011 (8:37 am)
Sounds as if you need to find another dealer. Porsche model change over is in late fall, September....
MDX is famous for torque converter failures and dealer is likely to be aware of that.
What is your reasoning for wanting a manual transmission Cayenne..?
It's an SUV, not a 911....
#25 of 29 Re: Just ordered manual tranny Cayenne [wwest]
Feb 22, 2011 (9:22 am)
We have always liked and driven manual transmission vehicles. Our 2008 BMW X3 was a manual and my wife, the primary driver, loved it. The X3 was not available when her lease was up and neither was the Cayenne base so we opted for the MDX. It was a huge mistake...the handling is just not the same.
Anyway, the Cayenne was supposedly the only German SUV available with a manual...though apparently it isn't.
#26 of 29 Re: Just ordered manual tranny Cayenne [ledname]
Feb 24, 2011 (7:35 am)
With the newer automatics yeilding better FE than a manual I don't think I'd ever buy another manual except in a true sports car wherein it will be "constantly" enjoyable.
#27 of 29 Re: Just ordered manual tranny Cayenne [wwest]
Feb 24, 2011 (7:42 am)
Everyone has their personal preferences. We prefer / enjoy a manual regardless of the type of vehicle (we don't live in a heavily congested area).
The other local dealer in our area was able to swap an "allocation slot" with another dealer such that they could order a manual for us. We are now deciding if we want to wait 4+ months or just get an X3 or X5 in 5 weeks.
#28 of 29 Re: Just ordered manual tranny Cayenne [ledname]
Feb 24, 2011 (10:41 am)
Wait...winter is almost over.
#29 of 29 Re: Just ordered manual tranny Cayenne [ledname]
by kyfdx@Edmunds HOST
Feb 24, 2011 (4:47 pm)
You can't get a manual in a new X3.. guessing that you can't get one in an X5, either....