steve_Cayenne

Short answer:

You will be fine in snow, just use proper winter tires as with any vehicle. And remember when hitting the breaks on snow and ice, your car has no memory of the 4WD that got it to that point except for the momentum. Momentum = mass * velocity = your enemy.

Long answer:

I had read a few reviews that the hybrid/diesel is not the most advantageous model off road (can't remember where so no links). Here is my take, and I am not a rock-crawler, or driveline specialist so I will happily stand corrected if somebody knows better.

Background: Because of the laws of geometry, there is a difference in velocity of the 4 wheels on your vehicle when not going in a straight line. As such there are differentials on each driven axel, and between front an back on AWD vehicles. These differentials typically transmit torque to the wheel with the least resistance, turning it faster. This works as your outside wheel needs to roll farther and faster, and has the least resistance.

A "stupid AWD" system, basically has all diffs "open" which works well enough on the road, but on say sand or ice: it will counter-intuitively transfer power to the wheels with the least traction (i.e. least resistance). These "spinning out" wheels will dig you in, and/or not move you forwards! A "slightly smarter than stupid" AWD system will try and fool the differentials by applying ABS breaks (creating resistance) to the wheels spinning wildly out of control … a bit better but no cigar!

A more proper 4WD system allows the differentials to lock (applying equal torque to all wheels). Locked diffs are bad for turning, but good for not getting stuck, since you are assured the wheels with traction (as well as those without) are all receiving power and spinning at the same rate. This can be:

Automatic locking (system trying to figure out what the hell surface you are on and what you are trying to do) … and may get it in between of right or wrong on road or off road. Wrong = reduced drivability on road or digging in off road.

OR

Selectable diff lock: lets YOU tell the car what you are trying to do!

Now back to Cayenne …

Hybrid/Diesel has a 60% rear 40% front split, and switches to auto-locking if it guesses you are loosing traction.
OK on road and off road.

Cayenne, S, Turbo: Electronically clutch controlled diff. Road use: computer controls (based on speed, acceleration, cornering force, traction, and steering angle) front rear split, and rear split with PTV option, for best driving dynamics. Hit the off road switch: diffs are all locked.
BETTER on road and off road.

RESP

Thanks for the clarification Steve.

alexaqui

Steve,

Thank you for the response. Very helpful. I know when I ordered my car I asked my dealer about which system it would use. They told me they thought it would be the same as in the V6 and not the hybrid. Not sure why they would do that for this model, especially given that in other parts of the world the diesel is viewed as more of the off-road model (at least that's what I've read!).

Doesn't sound like it will really impact me that much in the end. I bought it as a car to take my newborn along with my bikes and other gear. I also plan on towing my Cayman to events. Most of my "off roading" will probably be at triathlon parking lots!

steve_Cayenne

Totally agree, I was confused myself when I read that they did not offer their "for the toughest off-road terrain" option on the diesel, and hence asked if this was for real! I would think any die-hard off-roaders that want a Cayenne (all three of them???), would be very interested in Diesel because of its low down torque, and extended range. Then again, with their removal of the low-range transfer case on the new models, I guess they realize almost no owners would push their vehicles hard enough to even realize the fine nuances between these systems.

TexasRider

Steve your answer above was very good for 4WD and AWD drive systems and great work on finding out what the Cayenne does and bringing that forward for all of us.

I truly suspect several things have to do with Porsches selection of the system(s) for the Cayenne models.

The first is Porsches stance on options and packages throughout the different model lines. That is that the higher performance vehicles, with the higher prices, get the top performance options and parts. Porsche has always, since at least the 1980's anyway, been very conscious of how to separate the models, even if it is by a smidgen. Why does the Cayman not have a top shelf motor available like a 911? Because of that same philosophy to keep the 911 first. No matter that almost any Mustang GT crusing around can dust a Cayman , it has to stay behind the 911, or at least in the 911 owners mind . A Mustangg might dust him in the 911 too, but he does not want to even think of a Cayman passing him. Back in 1980's they had to detune our 951's to stay behind a 911. So I believe some of that is going on here.

I also believe they dont want too many of these cars too far out in the boonies. Can a Cayenne do some of it. Sure - and Porsche promotes this knowing full well that only a few are going to do that. But they dont really want to encourage it and have some more warranty work to perform. A CTT for $125,000 out there in the mess they know is not a large per cent. But a tractable diesel hooked to a better system .... Oooops ...... lets dont go there and something we dont want started.

I bet there are some other differences too, especially along the assembly line and parts handling that make it less desirable too. The 200 or even 500 of them that might be ordered with the really high price tag they are going to put on it does not warrant the changes in the assembly line process.

There could be some other small elements to the Cayenne models too that make it a bit harder, but that is probably the smallest part.

As you know I have been shopping the Mercedes 350 ML Blue Tec diesel too. Guess what - the Mercedes off road package is now Not Available in conjunction with the Blue Tec diesel for 2013. Think there are any secrets in the car business.

JFScheck

Yea - air suspension and weight displacing hitches don't match so keep tounge weight at 700 or below...

I have lots of posts about towing with avTDI over my Cayenne S - let's just say, end of the day - for my needs, a King Ranch f-350 can't be beat...

As for diesel Pepper - so glad they did it, my opinion - my oil burner out performed the Cayenne S for my needs with crazy fuel mileage!

blazing928

Range Rover have had auto locking center diffs for years. Much quieter and worked more reliably than the old air activated system. I see no issue with auto locking center diffs. Yes, I would like to have a locking rear in the diesel as well, or the option, like LR do for their cars, its a $1000 option for an active rear diff.

[edited]

PDCC also detatches the anti roll bars when in off road modes to achieve better axle articulation.

In essence I feel Porsche don't believe the diesel will be driven as hard as a CS or CTT, so the more basic system is ok. Or they are using up old stock.....

I wonder how long rear brake pads last when driven in slippery conditions. With the Ferrari 458, they are using a set of carbon disc on a track day as the traction control uses the rear brakes constantly! Many owners are changing to steel discs.

That article I wrote about from Car Magazine, was extremely complimentry about the off road diesel, almost aas good as the LR D4. Better than X5 & new ML, not only off road but of course on road.
Its interesting in that they felt the cayenne had the best ride!

steve_Cayenne

Ok, so come to think of it, I guess what I may be more surprised at is that the lowest end V6 comes with the fancier driveline!

alexaqui

It really is a shame. When I picked up the car, my salesman said that it doesn't make sense and that my information is most likely wrong. Sure enough, when we got in the car and he showed me how to work everything, we confirmed that it has the automatic system that the hybrid has.

At this point, I'm happy as a clam anyway. The car is a great package and I'm not going to let myself be disappointed by the lack of a feature I probably don't need.

tripleblack

This is a very useful thread. Some P-car sales folks appear uninformed of the driveline nuances.

CO-rayman

Interesting info guys. It seems that for 2013 there may be some differences. More specifically, it seems that the CD and "S" hybrid transfer torque between front and rear axles when slippage is sensed as well as PTM enabling variable distribution of engine torque to the rear wheels.

I am new to CD so I really don't know if these combined features are the same as the previous years but it seems like the description below covers splitting torque between the axles.

Here is some info from porsche.com:


>>>>>>>>>>>>>>>>>>>>>>>>>>
Porsche Traction Management (PTM): Active all-wheel drive with electronic and map-controlled multiplate clutch with automatic brake differential (ABD) and antislip regulation (ASR)

The Cayenne Diesel and Cayenne S Hybrid feature a permanent all-wheel drive system with self-locking center differential. This provides a standard torque split of 60 percent to the rear and 40 percent to the front. If one of the wheels is about to lose grip, the self-locking center differential transmits the torque to the axle offering the highest level of traction. The ASR and ABD systems work in the same way as in the PTM on the Cayenne, Cayenne S and Cayenne Turbo.

On the Cayenne Diesel and Cayenne S Hybrid, PTM also enables variable distribution of engine torque to the rear wheels, thereby enhancing steering precision and driving dynamics. Specifically, this means that when entering a corner at high speed, moderate brake pressure is applied to the inside rear wheel. This supports the steering motion of the car, thereby improving its cornering dynamics.

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