VIDEO: Quattro Vs. xDrive, FIGHT!

impressed with the xdrive but maybe the tires were bald on the quattro ??

No the tires weren't bald.

This is a very controlled situation where in fact the quattro is at a disadvantage. However in the last 8 years driving a quattro I have never had this happen to me, even remotely close.

Does it happen? Yes
How often? Rarely

Can a similar situation hamper the X-drive? Yes, just search youtube.

like this one,
http://www.youtube.com/watch?v=3Dt8J_lTNjY&NR=1

and in the quattro system you apply the brake with the throttle in this scenario and problem solved....

I don't know if the video is biased in ramp approach, vehicle modes, or special design of ramp, but I'm just glad that there are systems in cars these days that can work and actually help as an assistant.

It is not bald or worng tyres. The wheels that should be working are on rollers (~zero resistance), therefore the test is to see if the cars will send the drive to the other wheels that have grip (~resistance)

I don't know enough about the systems used on either car, but I'm guessing the only way the test could be rigged, is if the system on the Audi were disabled? However, a much simpler explanation, is the BMW system simply works better when one pair of wheels has no grip at all.

if I remember correctly, the newest version of xDrive can send 100% of the power front to rear and vice versa, so the X3 can be front wheel drive, rear wheel drive, or anything in between depending on the conditions. Quattro in the Q5 does (I believe) a maximum split of 70:30.

Ahhh! The BMW marketing mavens at their best.

Of course it's nonsense, how many roads have you see with rollers in them? The quattro system is a simple mechanically operated system that is torque-based. If you have 1 axle on rollers (just like the A8 vs 7series demonstration) the system is "disabled". Basically you would have to have both wheels on solid ice with ZERO traction for this to happen in the real world. I don't see that happening otherwise I'd imagine the BMW people would be smart enough to show that...and if so simply operating the brake with the gas will send power to the other axle.

Nice try....

well, I suppose you're right, I don't think you're going to see many roads with rollers on them. But when there's ice/snow involved I don't think it's that uncommon to have two or three wheels with traction and one or two without. That's why both Quattro and xDrive are designed to proportion the torque between the front and rear axles, and that's what was being tested in that video. In a frictionless environment xDrive can trasfer 100% of the torque to either axle, and 50% to one wheel (more if the car has DPC, like the X6). Quattro can only transfer a maximum of 15% or 35% of the torque to one wheel, depending on which axle the wheel is on.

There's a big difference between zero traction and poor traction from snow or ice, the Audi system doesn't perform poorly in poor traction, just ZERO traction on one axle.

Again if BMW wanted to show real-world scenarios they would have but I'm sure we know the results. How about a video of all the cars trying to drive up a ski slope when the allroad goes to the top....might have been rigged but this one is definately rigged.

"There's a big difference between zero traction and poor traction from snow or ice, the Audi system doesn't perform poorly in poor traction, just ZERO traction on one axle."

I see. So if I understand correctly, your argument is the Audi system doesn't work well when there's zero traction, but works fine when there's limited traction, and that makes it superior. I don't understand that though. If the BMW system works well when there's zero traction, which you're admitting the Audi does not, it would seem logical by extension xDrive would also work well when there's more than zero, right? So basically both systems would perform well when there's limited traction, but only one (xDrive) can still perform well when there's even less than that. How is that a "win" for Quattro exactly? Wouldn't the "better" system be the one that can do more than the other, the one that can still benefit you when the other one can't? Even if it's "unlikely" that you'd face those conditions (and I disagree with that), wouldn't it be better to have the capability just in case? Better to have it and not need it than need it and not have it, right?

This demonstration shows nothing about real-world driving conditions, and notice I didn't say which one I thought was superior.

Just saying it's a total gimmick set up by BMW to make it look their system is superior in a non-realword situation. You can say it simulates one all you want...why did't they do this on a skating rink or feeze some water on a inclined driveway, 'bought as bad as you are going to see driving on the road. The roller trick has already been done.

No, just becasue one car can get out of an all-to-common roller-in-the-road trap doesn't automatically make it a superior vehicle, but I don't think you are going to see it that way...

again, both can do what the Quattro system can do. One can do more than that. That means the crux of your argument is that the extra ability will never be needed in the real world and is therefore worthless, and again my response to that is
a) I disagree, and
b) I'd rather have the capability and hopefully not need it than need it and just plain not have it.
I'm not knocking Quattro, both systems might be totally great in 95% of conditions. But if I can get that last 5% then I'm not going to spit at it. It's still a benefit.

But we don't know how they perform in real world conditions, at least not from this, and this isn't 5% of what you'd encounter while driving, it's 0%...

I can't see the video at work but I think this is the one...

www.youtube.com/watch?v=ii_fXvg98w4

it might be rigged, the BMW definately is...

I agree with Jrob. If you go onto youtobe you can see countless examples of the quattro system not working well when confronted with a situation of Zero traction .... I would rather have complete 100% capability rather than having none at all. Why settle?

The quattro system excels in Muddy and climbing up a ski slope. Neither of which I will ever encounter. Has there been some instances when on a hill on ice where traction was almost none, yes. The systems differ greatly, to where the BMW xdrive is far superior ...

I was suprised by the test ...

aarononymous-

Nice try with the video, to bad it's real old and the BMW doesn't have X Drive.

Ok I think this one has x-drive...watch the end and tell me what went wrong...

http://www.youtube.com/watch?v=3Dt8J_lTNjY&NR=1

looks kinda like the scenario above?

blah blah tires blah blah....

aaron ... you are a goof. That is an X6 with 20" performance tires on it, which everyone knows that performance tires arent worth a damn in the snow or ice. It doesnt make a difference if you have AWD, FWD or RWD with Performance sport tires.....

nice try, better luck next time ....

guess I need a better monitor, couldn't read the sidewall, and anyways most BMW's (and Audi's) don't use low profile tires...

maybe you'll like this one better...

cars.
driving.
on.
ice.
http://www.youtube.com/watch?v=_GDJYNiRWDg

just like on rollers...

sorry..still not satisfied with the roller demonstration

aaron .... so driving on a pond is a realistic driving conditions? lol ... you are such a goof.. next you will copy the Audi driving up the ski slope to prove your point ...

A perfect example of what a locking center differential does. The rollers aren't a gimmick. It is a simulation of driving over a patch of ice on a hill.

it is a gimmick, and you mean stopping on a patch of ice and starting...if that's the case they could easily make a video showing this...

"if that's the case they could easily make a video showing this..."

they did. You just watched it. You just don't like the results.

yes... aarononymous... like people don't stop on hills... have you ever seen a traffic light before? Or tried parking on a hill where the engine melts the snow beneath you and it refreezes into a nice and slippery pane of ice?

That's exactly what I'm saying buddy, show that if you want to have an effective demonstration for intelligent people...I think it would be just as easy to set up.

JRob, rollers /= ice...you should be smart enough to know that

aaron - how is this test not an intelligent one? It is a controlled experiment to show power transfer and the AWD capabilities or limitations. Unfortunately for Audi, it showed a great limitation in their AWD system. Basically, if you are on a hill at a standstill, with a sheet of ice beneathe your rear wheels, that with the Audi you will not be able to move unless you slightly roll back to get some traction.... huh?

you're right, they should carry a frozen mountain around with them to show the test in "real world conditions".

FYI, I have seen videos of vehicles doing exactly what you're saying -- going up an actual hill, with bands of snow/ice across a whole axle or under just one wheel. If you can test everything in a static location and get the world to come to you to witness it, that's great. Sometimes you can't get the world to come to the mountain, though, you have to bring the mountain to them. That's what this test was.

J-Bub don't be overly dramatic, nobody is asking for them to bring a "mountain". I think BMW has enough money and if it was superior think how good a marketing strategy it would be to show a snow-covered driveway inclining to the road, a sheet of ice at the bottom from the gutter, etc...same scenario just real-world. It's winter once a year in the US, hell I even think they make snow nowadays! Why didn't they think of it?!?!

Again notice I didn't call the quattro system superior...yes I think it is, but I don't drive on rollers so to me this is just a simulation, and a poor one at that...

uh huh. So basically you're admitting you have a problem with the test because of your blind allegiance to Quattro. Conversely then I'm going to go out on a limb and bet that had the results of the test been reversed, and the BMW couldn't get past the rollers but the Audi could, you'd have no problem with the demonstration.

It's a "travelling demo". So compared to real world it has several benefits beyond the ability to actually take that contraption around and let people experience it. For example, you can configure the rollers to offer more or less resistance (that's "friction" in the "real world" for you). You can't do that with a frozen mountain, or a frozen driveway, and again, you can't cart a frozen driveway or mountain around the country. They tend to be stationary. And whatever "friction" setting they had the rollers at, the BMW was able to get past them, the Audi wasn't. End of story. Go drive your Audi up a mountain, and good luck to you should you run into a patch of ice with friction as low or lower than whatever those rollers were at. Just make sure you bring a cellphone so you can call someone with a BMW to come get you if you do.

Does audi still use torsens in their quattros? They can handle usually handle a torque bias ratio of up to 3:1 meaning that the road doesn't need to be zero friction, it simply needs to have three times less traction. Considering that in the winter cars create black ice zones at intersections due to constantly remelting and freezing the ice. This is far from a not common scenario... of course this assumes audi is still using torsens (which is what it looked like in this video)

They use both Torsen and Haldex

I thought xdrive used an active clutch plate differential?

Joe, you are thinking power distribution...you need a whole axle with ZERO traction, not a third, not ice...just like in the video

aarononymous. No you are wrong. If a torsen can only split it's power that much, and the situation requires more splitting, it will lose all drive to the side that isn't spinning out.

why doesn't it just continue applying the majority of power to the wheels with traction, you're saying it just gives up?

It requires the frictional preload in order to properly split the torque. We had a torsen in our fsae car and whenever we would pull very hard corners and the inside wheel would start to lose traction the torque on the outside wheel would abruptly die. It's an amazingly simple purely mechanical system for when you do have a fairly even load distribution. But it does have it's limits, and it is not fun when you exceed them.

but you still have friction unless you have zero like in the video

No, you still need the bare minimum 3:1 friction level. If it could still supply torque to the outside wheel with 4:1 friction levels, then clearly it would be rated with a torque bias ratio of 4:1.

I know I mentioned it in the third post, but we should probably clarify zero resistance... the're will be some drag in the rollers..depends on how good the bearings are.


.. unless BMW invented zero friction bearings just for this test, in which case.... that would be amazing.

it's going to sense torque unless there is zero, it will send the power to the wheels with the best traction and the remainder will get the 33% or less depending on the version of quattro. Don't forget EDL if you have one wheel with poor traction....

there will always be torque silly, even if it were imaginary perfect bearings everywhere. There will still be torque applied to cylinders to counteract their inertial effects. On a sheet of ice, there isn't as much inertial loading. So if the ice was slippery enough there would actually be more force being applied in a roller with imaginary perfect bearings!

And no, you are absolutely wrong. If torsens worked that way, you would stall an engine by locking only one of the wheels and allowing the other to free wheel. You seriously need to go read up on them. Or learn physics. If one end is slipping (even on a surface with a bit of friction) the other end will not get the remaining 75% (3:1 is split 75-25 not 66-33) If that was the case, you would get torque ratios higher then 3:1, which again Torsens are NOT capable of delivering.

you obviously know more about it then me, maybe you can explain in terms I can understand because I feel like we're not on the same page. The Audi system only uses a torsen center diff and open front & rear diffs. So lets say the two rear wheels are on ice and more than 75% of the torque is required at the front axle (as you said, correct?). Wont the torsen just send 75% to the front the rears will recieve 25% and continue to spin and the fronts will pull the car forward if they have enough traction. Please explain why this isn't true and what will happen in simple terms. Also I don't understand how locking a wheel will stall the engine, that's how EDL works...

Ok, basically, the torque applied needs to be counteracted. The way you are thinking of it is that you simply apply 75% torque to the front and 25% to the rear. But to apply 25% torque to the rear, there needs to be a traction force capable of withstanding the 25% of the torque, if it doesn't the wheels will simply spin out and the torsen will act like an open differential. Now say you are on a hill with ice. You need a certain amount of torque to be able to get up the hill, any less and you will roll down. If the ice patch isn't capable of supporting 25% of the total torque needed to move up the hill, the torsen will act as an open differential and you will get no where.

Now the reason why it will stall the engine. Say you had a gear box with two shafts coming out of it and one going in from a motor. What I am visualizing is one shaft being geared to have 75% of the incoming torque, and the other to have 25% of the incoming torque. If you fix either of the shafts, they will stall the engine. This is how I visualized your description of being able to limit the torque to on one side to only 25%

for your second point EDL works on the open diffs, not the torsen diff...if your right rear is on ice and the other 3 have traction it will apply break to RR and through the open diff and center torsen diff power is transmitted to the other wheels.

as for the second point is there a difference between a car requiring a certain amount of torque to a front or rear axle and what it can actually send. The torsen doesn't know it requires more than 75% to an axle or needs less than 25% to the other, it just sends to it's max in that case. I don't see a torsen acting as an open diff unless it's on a set of rollers( or if an axle breaks). I'm going to experiment this winter when we finally get some snow.

What the torsen does in that scenario that causes it to act as an open differential is it takes the input torque and tries to apply it to both ends. The end with extra traction gains more torque, and it will try to send less torque to the other end until it reaches 25%. Now lets say there is enough traction on one end of the vehicle to support 20% of the torque being applied, the wheel(s) will start spinning since they are receiving 5% too much torque. This 20% traction can be multiplied by 3 (due to the 3:1 ratio) to get an applied 60% engine torque instead of 75% on the front wheels. And then you are left with only 80% of the torque required to climb the hill. If you apply more torque with the engine, the end with the traction won't be able to use any more of it since the back end will still limit it to three times the tractive torque seen on the slipping side (which is actually decreasing with increased wheel spin). The end result of which is having the torsen spin out like an open differential and the vehicle moves no where.

guess that's where the brake pedal comes into play?

I guess... but that's pretty sketchy. A better awd system wouldn't have to use the brakes to engage traction.... that's like having to shift a car into neutral to stop sudden acceleration...

also... couldn't you use live differentials everywhere and use brake vectoring to control individual wheel torque? It wouldn't be efficient but it would get the job done lol

I don't think it's really that sketchy, how often is it really neccessary, not theoretically....

so do you think open diffs with brake vectoring wouldn't be sketchy? It would give you the same effect but it would be far cheaper to manufacture.

if this example is so revealing for BMW then why not show it in the REAL WORLD and not some rigged up contraption. If this is all BMW has, then it shows nothing more than a fixed and biased video which demonstrates nothing. Why not PROVE it where it counts, in the snow and ice and add uphill while you're at it. BMW could have done it, BUT THEY DIDN'T.

It seems that this is a 'road show' style set up, meaning they can drag it around to events, launches, etc. The video is not a BMW oficial video, it was not designed to be distributed as a web video by BMW, it was designed to show people there and then what the system could do...

.. being practical, you are not going to be able to do it that easily with real ice (yes it's possibe, but not really practical - when you can just use rollers!)

Mean - You mean climbing up a ski slope or Ski jump ramp as Audi does is a 'Real World Test"? ... huh?

Actually the test does represent a real test. If you are on a slight incline as you come to a stop & there happens to be a good amount of ice on the road. You step on the gas to accelerate from a stop light and your car hesitates cause it cant transfer power or enough of it to the wheels that have grip. Where as the BMW, does it in miliseconds and accelerates smoothly ... How is that not a real life test? and yet you claim driving up a "Ski Slope or Ski Jump Ramp is?

again, very surprised by how this test went & all the others on You tube that i researched

Well, I figure the reason they do it on a ramp is to make it so it requires more torque to get up the hill, therefore highlighting a weakness in the Audi's system (ie, it is not able to transfer enough power to lug it up the hill).. so I think this is a genuine test, with no trickerery, just highlighting a specific situation in which the X3 will out perform the Q5.

I agree it would be more valid for them to have just used a slope with bands of ice across it, at least it would have looked more plausable.

.. and by the way, 00R.. BMW had always planned to provide xDrive versions of the 5GT, just not as launch models.. you make it sound like BMW did it as a reaction to the north eastern US market..

don't forget you just apply the brake to the Audi and problem solved on the rollers

My 2009 Jeep Wrangler Rubicon has locking differentials on the front and rear. So you can put ice rollers on 3 wheels and I can still make it up zee Hilll JA!!! Why? Well it's all locked up no computers, no wizbang german engineering b/s, SIMPLE LOCKERS ON american dana 44 AXELS'S. HURAH!

No Subaru tested.
Germans are afraid of Subaru?

If it's pro-BMW then it's bias. It's as simple as that.

"I see. So if I understand correctly, your argument is the Audi system doesn't work well when there's zero traction, but works fine when there's limited traction, and that makes it superior. I don't understand that though. If the BMW system works well when there's zero traction, which you're admitting the Audi does not, it would seem logical by extension xDrive would also work well when there's more than zero, right? So basically both systems would perform well when there's limited traction, but only one (xDrive) can still perform well when there's even less than that. How is that a "win" for Quattro exactly? Wouldn't the "better" system be the one that can do more than the other, the one that can still benefit you when the other one can't? Even if it's "unlikely" that you'd face those conditions (and I disagree with that), wouldn't it be better to have the capability just in case? Better to have it and not need it than need it and not have it, right?"

The key to success for Quattro is not some traction, but the limit traction differece between frot and rear. On the solid ice for example, all wheels get traction even near zero, but as long as the differeces are within the ranges 15%-85% and 65%-35%(front to rear), the car can go. In these kind cases, Quattro is better than xDrive for its all time feature.

Ok peole listen up i did the following test with my 2006 audi quattro a6. as far as ice goes my driveway is steep so i iced the top part on a very cold evening then pulled out of my garage and stopped the front wheels on the ice and it went forward without even the traction control light coming on, then i hosed the bottom part of the driveway to have ice again and this time i had some wheel spin no drama and the car went forward, i have never got stuck in my car and it is a hoot to drive on black ice, just last night i was driving 60mph on black ice(i knew because i just tapped the brakes and the abs came on) and the esp did not even activate this is a very safe car(remember braking is near zero on black ice, keep a safe distance) and a blast to drive much more so in adverse conditions i only give bmw (having had a bmw z4 as a summer toy to be fun to drive)but the audi quattro is second to none for traction and high speed control on ice and snow, i'm tired of these stupid tests, go out and drive your quattro on the roughest conditions and see what it can do, quattro owners know what i'm talking about and when they pass cars that can't even get up icy roads and just cruise by with no drama at all are laughing and enjoying all the magic hapenning under our pants. i'm always amazed at what my car can get through, i only get stuck when i'm trying to go through 3 foot high snow banks for fun and get stuck because the car gets hung up, that is where a jeep would be handy but even 6 or 8 inches of snow is not a problem it is not a off road vehicle and does not have the torque a rubicon has off road, but is very comfortable on long trips and is fun to drive slow or fast in snow and ice. love it. but even having traction on the other axle is way better then fwd or rwd on it's own, quattro just takes it to a whole other level.