Does Off Road Mode provide more grip in snow

[Sideline]

As they say, unlike winter tires, in slippery conditions, AWD may help you go, but it won't help you stop (nor in many cases keep you from sliding sideways or spinning, either).

Another thing to keep in mind: at least in my Macan 4, under normal circumstances, Normal Drive mode only drives the rear wheels. I assume once slip is detected, the fronts start driving also; I don't know how long that might take (milliseconds? Tenths of seconds?)

Remember, in the Trip view on the PCM, there is an animated graphic showing both power distribution and energy recuperation. Interestingly enough, one thing you can see is that changing to Sport mode starts driving all 4 wheels. I haven't played with this at all but I assume Off Road mode would also drive all 4 wheels, and slippage or hard acceleration would do so in any mode as well. I presume that someone who wanted to play could see all this on the PCM view.

I must be thick because I can't find that view you mention that shows an animated graphic of power distribution. A little help please?

 

[ColdCase]

I would not use Off-Road Mode for driving on snow and ice, just let the traction control handle wheel slip should it occur. In your driveway Off-Road Mode may not make any real difference, but on the road it could cause problems because it could lock the left and right wheels together so they turn at the same rate, which can interfere with steering. The last thing you want in a curve on the road is understeer into a ditch or oncoming traffic.

From the manual:

I read this as a more aggressive/different ABS strategy. The wheels are not locked together, but the brakes lock both up for a brief moment to dig in to better traction and hopefully provide better steering. One could use this in deep snow where the tires are slipping regardless (i.e. no steering) so you lock up the brakes to dig in to hopefully better traction and then steering. Works sometimes. Applying throttle can pull you through, however, if you have that option.

As far as I know, and thats not saying much, only the rear axle with the PTV+ option can lock the halfshafts together by locking the differential.

I dunno if off-road mode is useful on snow. Our Jeeps use a quite different traction algorith for snow and off-road.

 

[dgkhn]

I must be thick because I can't find that view you mention that shows an animated graphic of power distribution. A little help please?

I'm not at the car right now, but Car/Trip in the PCM.

Pretty sure (99.99%) AWD is active all of the time and never 2WD. No different to Macan ICE or other AWD Porsches including the Taycan.

Go to screen referenced above, drive "normally" and tell me what you see. In my car, I see only rear axle is powered. Change to Sport, and then both axles are powered.

 

[PanameraFrank]

I'm not at the car right now, but Car/Trip in the PCM.


Go to screen referenced above, drive "normally" and tell me what you see. In my car, I see only rear axle is powered. Change to Sport, and then both axles are powered.

There is generally always a small percentage of power to the front, like 5% or less. There isn't a true axle disable like Range mode in the Taycan.

You are correct that the rear axle drives the car in normal use, but the front axle is still active, just very slightly.

 

[SergeyIndy]

I must be thick because I can't find that view you mention that shows an animated graphic of power distribution. A little help please?

Car > Trip

The graphic is helpful to see if motor is on/off, power draw (blue lines to motor), or regen (green lines to battery).

 

[PrudentOcean]

As far as I know, and thats not saying much, only the rear axle with the PTV+ option can lock the halfshafts together by locking the differential.

Yes, at the front axle traction are probably controlled entirely using the ABS system and brakes -- if the sensors detect a significant increase in wheel speed due to slippage, the brake is applied and torque goes to the wheel with more traction.

The exact logic of how much slippage to allow and how much brake to apply is not something Porsche talks about, but they do mention the possibility of a brief lock-up of the front axle, and that would definitely be detrimental to the ability to steer.

 

[dgkhn]

There is generally always a small percentage of power to the front, like 5% or less. There isn't a true axle disable like Range mode in the Taycan.

You are correct that the rear axle drives the car in normal use, but the front axle is still active, just very slightly.

This is why, when I first saw the Car/Trip graphic, I was surprised to see that it indicated no power to the front axle.

Now, Porsche is not clear about this (or, maybe they've never said at all). We know the Macan does not have a clutch, and from what I understand, the front motor is a permanent magnet motor (well the rear also, actually); these two facts together imply that the motor cannot be completely inert (at least that's my understanding); there always has to be some current flowing to through it. I guess the question is, how successful has Porsche been in limiting parasitic losses when the front motor is at its minimum current draw?

 

[ColdCase]

they do mention the possibility of a brief lock-up of the front axle, and that would definitely be detrimental to the ability to steer.

Locking the brakes can be detrimental to steering if you had enough traction to steer effectively, like on dry pavement

But with no traction there is no steering to adversely affect. Just trying to say that the feature is not always detrimental to steering and may be useful "off road" .

You can see this sometimes when driving on loose shale with wide summer or AS street tires. Those tires combined with suspension geometry tend to role over the shale (like rolling over marbles) instead of digging in, so spinning the tires or locking them up briefly will break the "surface tension" and allow more effective steering. Locking both up at the same time is usually more effective than the typical asynchronous ABS brake application. These conditions show up often enough off road and in ski slope parking lots that it is probably worth the effort.

 

[rcomeau]

The idea of the momentary locking of the wheel is to try to get from kinetic friction to static friction. When there is no motion between the two surfaces, the friction is much higher (the textures of the two surfaces interlock more) than when there is motion (no interlocking of the surface textures). Thats why once yo start sliding, it if harder to stop. Lock the wheel and get to static friction, and you are more likely to remain in static friction and regain control.

 

[W1NGE]

I must be thick because I can't find that view you mention that shows an animated graphic of power distribution. A little help please?

You could research the Owner's manual but go to Trip settings in PCM and you'll see the graphic depicting green flow for recuperation and blue for energy consumption.

 

[Sideline]

You could research the Owner's manual but go to Trip settings in PCM and you'll see the graphic depicting green flow for recuperation and blue for energy consumption.

Goes without saying that I could research the Owner's manual; my post was a quick response to a live discussion. I was confused as I thought the animated graphic was in the instrument cluster, not in the central display. I did quickly find it once I realized my mistake. But thanks for your response.

 

[LivingTheDream]

I think a quote from the Porsche Newsroom article on the Macan's chassis systems is relevant to this discussion.

Here's the quote...

Porsche Traction Management distributes drive power within milliseconds
The two electric motors in the all-wheel-drive models of the new Macan are controlled individually, and almost in real time, via the power electronics. The electronically controlled Porsche Traction Management (ePTM) operates around five times faster than a conventional on-demand all-wheel-drive system and can respond to slip within 10 milliseconds. In addition, the torque distribution is governed by the selected driving programme. In ‘Normal’ mode, the drive distribution is designed for high efficiency and range. This means that rear-wheel drive is used as often as possible. In Sport and Sport Plus modes, the focus of the ePTM is on optimising traction; the drive on the front axle is engaged more frequently. In off-road driving mode, the Macan switches to all-wheel drive with a ‘rough road’ configuration. The differential speed between the front and rear axles is limited by a virtual centre-differential lock, which improves traction. In addition, High Level I is activated, increasing the ride height by 20 mm. A lift of 40 mm is achieved in High Level II.

 

[LivingTheDream]

Another thing to keep in mind: at least in my Macan 4, under normal circumstances, Normal Drive mode only drives the rear wheels. I assume once slip is detected, the fronts start driving also; I don't know how long that might take (milliseconds? Tenths of seconds?)

From the Porsche Newsroom article I reference above...

The electronically controlled Porsche Traction Management (ePTM) operates around five times faster than a conventional on-demand all-wheel-drive system and can respond to slip within 10 milliseconds.

 

[W1NGE]

I think a quote from the Porsche Newsroom article on the Macan's chassis systems is relevant to this discussion.

Here's the quote...

Yep - so both motors are in play but the emphasis on power distribution / bias shifts to be predominantly RWD in Normal drive mode which is what. I said earlier.

No different to Macan ICE except the distribution / bias is greater as the Macan EV is much faster to react (electric rather than mechanical) should conditions require it.

 

[SuperH]

Having done my complimentary track day at Silverstone in the snow, all you need to do is take it steady and the car wizardry does the rest. As others have said, although you did mention you're a cautions driver already, just don't thrash it and you should be fine

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