Jet Jockey/A4 Pilot

Not necessarily true. A lot of factors have to be taken into account.

Epiplatys

I'm off-roading a bit, so I'll chime in if that's OK. Ground clearance will be critical, as well as good 4WD. Both cars have good 4WD, but one does not have the ground clearance.

Locking diffs on snow is a very very arguable proposition. I personally never do it. I might do low gearing if the going gets tough, but never locks on slippery surface. The traction control, stability control and dynamic torque distribution is your best bet. Locking the axles only leads to unnecessary slides, loss of traction and control on snow. Just don't do it if you not looking for problems.

John Stahmann

The problem with the traction control, stability control, etc is that it limits power to the wheels which is a problem when you're trying to plow through snow. When you'd try to power through deep snow the traction control would actually fight the wheel spin and cause you to get more stuck. The best thing in that case was to turn off the traction control, lock your diffs and power through.

I can appreciate what you're saying, but from first hand experience in our Touareg I can say that the locking diffs made a huge difference a few times in really deep snow. Obviously one wouldn't lock the diffs driving around town.

Epiplatys

Well, I should have considered the regional difference. I live in the mountains, so there is practically no even flat road sections here. If you tried to lock the diffs (and trust me that was the mistake I was making too when I was a beginner), you are getting yourself into trouble. With the diffs locks the vehicle becomes extremely likely to skid, and slide downhill. Unless you are on a flat even surface. Even then I'd use more throttle and power my way through. The stability control actually knows when you are in the 'off-road' situation and changes the algorithm (at least on mine), so it does not stop the wheels or rub them of too much power. It works. I have to test this ability almost every day in winter: my place is 440m (150feet) up the hill, over 2 mile distance. So sliding up and down daily is what I do. Lots of tight turns and uneven bends. Snow can be 2-3 feet some days, but half a feet is more typical. As you can imagine, I have plenty of opportunity to watch how other vehicles are doing

John Stahmann

I live in the mountains too. I guess we just have different experiences with the same thing...

This is what happens when the traction control kicks in, tries to kill wheelspin on an icy road, and you lose momentum to the point that the vehicle literally stops and then starts to slide backwards even though you have the accelerator floored. This would have been avoided had I turned off the traction control...

<img src="http://www.stahmann-motorsports.com/vw/touareg/slide/slide1.JPG">

<img src="http://www.stahmann-motorsports.com/vw/touareg/slide/slide2.JPG">

Epiplatys

Ah, got it. I have the traction control on my Mercedes working the same way. It just would not be able to climb the hill and stop. I have to tug it up with the rope. Don't know if the RS4 does it same way, will see soon.

But the one on my 4x4 works entirely differently. It does not stop the wheels, the cars continues to climb and never stops. Just corrects any slides etc. In the manual they specifically mention this as well: off-road mode traction control. You do have to have certain momentum of course, laws of physics are still in effect.

Epiplatys

It is still snowing a bit. Probably half a feet of snow today. The roads are covered.

So... I'm still on the Pirelli P-Zero, no winter tires, so take it as such.

Going downhill is not easy and slow. The RS4 has considerable weight, plus snow tires. Going 5-10 mile per hour most of the distance, and still - very little stability and brakes are next to useless. The car would not stop, continuing to slide downhill actually even accelerating a bit. So keeping it on 1-2nd gear and a bit of gas helps to stay on the line, but stopping is out of question.

Doing uphill on the same road - going up with flying colors. No issues whatsoever, summer tires or not. Practically no wheel spin, no drifting, no nothing. Really fun to play doing a bit of slides here and there just because you can.

In comparison: the rear wheel drive Mercedes is not able to climb half the distance is this weather. Whatching all the BMWs etc - same story. On the other hand - the 4x4 truck on all-seasons seem to retain the steering and breaking abilities better downhill. At least it is able to break to stop, and does not wonder around. Now - don't laugh: Honda Insight (have in the family) - is literaly flying up and down the hill like there is nothing special on the ground. Skinny tires, weighs next to nothing and front wheel drive. Amazing.