[VIDEO] xDrive, how it works?

[bigjae1976]

Originally Posted by JNoSol

+1. Audi was first to use AWD in rally racing, so they market the shit out of that claim. Today, factually, they're not the best. In road racing, Audi will disappoint as it will understeer (FWD biased) which isn't favorable. It is not as fun to drive a car that understeer. BMW xDrive is RWD biased, which makes it feels more like a true sport car as it still easily oversteer.

Notice the second video (above) traction test favors BMW, as they place rollers in the 2 front wheels of the Audi. BMW is RWD biased, so it got out much easier even with on rear wheel touching the pavement. That is true proof that Audi is FWD biased without much research.

I have an F06 xDrive, it truly feels like a RWD with more confident through corners.

xDrive vs Quattro below, probably a slightly biased review but still factual.

http://www.bimmerfile.com/2014/06/02...s-the-audi-s4/" rel="" target="_blank">http://<a href="http://www.bimmerfil...e-audi-s4/</a>

Exactly, BMW does not market xDrive as a performance attribute like Audi does.

I'm willing to guess that it would really send the BMW RWD "purists" over the edge. The M division is apparently toying with an AWD M5...rather reluctantly. Could you imagine the uproar and AWD M3/4 would cause? Look at what's happening with turbo engines.

[PackPride85]

I didn't listen to the audio in the 2nd video, but these tests kinds of tests are completely bogus. Audi's system uses a Torsen (aka torque sensing) center diff. It's a purely mechanical set up that will multiply existing torque on one axle by some factor and transfer it to the other axle. The key is that there has to be some small amount of torque present or else 0 x 0 = 0. Despite that, its still a great system and is easy/cheap to implement. The transverse mounted audi's use haldex which is an xdrive type clutch setup.

Xdrive uses electronically activated clutches to engage the front axle (no true center diff), thus being able to transfer 100% of the torque to either axle even in 100% slip conditions (usually maintains a partial lock to maintain a rear bias of 60/40 I believe). Is it better than a torsen system? In the extremely unlikely event (and by that I mean impossible) that you have ZERO traction on BOTH wheels of an axle, then yes xdrive is superior. The fact that it uses sensors means it should be able to "detect" slippage before lost of traction (using steering angle, throttle, etc...)as well is another advantage.

What's really more important is the traction between wheels on each axle. Most of these cars with open diffs and traction control will brake the spinning wheel to transfer torque across the axle. My guess during this test was that they disabled that for the Audi and left it enabled on the BMW.

If you want a true performance AWD system look at a WRX STI. An adjustable viscous coupling center diff, which while slower to react can transmit torque in complete no slip situations, and torsen LSD diffs on the front and back (pre 2011). That setup blows the doors off xdrive and quattro.

Honestly, I think actual awd performance for quattro vs xdrive has more to do with how the DSC is programmed for same axle traction and tire size/type instead of how the power gets to each axle. If BMW wanted to throw an mechanical LSD or two along with Xdrive it probably would make a formidable performance AWD system.

[Gonven]

It's seems they putted the video in private meh

[autopal]

Originally Posted by PackPride85

I didn't listen to the audio in the 2nd video, but these tests kinds of tests are completely bogus. Audi's system uses a Torsen (aka torque sensing) center diff. It's a purely mechanical set up that will multiply existing torque on one axle by some factor and transfer it to the other axle. The key is that there has to be some small amount of torque present or else 0 x 0 = 0.

Xdrive uses electronically activated clutches to engage the front axle (no true center diff), thus being able to transfer 100% of the torque to either axle even in 100% slip conditions (usually maintains a partial lock to maintain a rear bias of 60/40 I believe). Is it better than a torsen system? In the extremely unlikely event (and by that I mean impossible) that you have ZERO traction on BOTH wheels of an axle, then yes xdrive is superior. The fact that it uses sensors means it should be able to "detect" slippage before lost of traction as well is another advantage.

What's really more important is the traction between wheels on each axle. Most of these cars with open diffs and traction control will brake the spinning wheel to transfer torque across the axle. My guess during this test was that they disabled that for the Audi and left it enabled on the BMW.

If you want a true performance AWD system look at a WRX STI. An adjustable viscous coupling center diff, which while slower to react can transmit torque in complete no slip situations, and torsen LSD diffs on the front and back (pre 2011). That setup blows the doors off xdrive and quattro.

Honestly, I think actual awd performance for quattro vs xdrive has more to do with how the DSC is programmed for same axle traction instead of how the power gets to each axle.

Very informative post. I'm very curious, how similar, or different is MB 4Matic?

[ap1]

Originally Posted by PackPride85

I didn't listen to the audio in the 2nd video, but these tests kinds of tests are completely bogus. Audi's system uses a Torsen (aka torque sensing) center diff. It's a purely mechanical set up that will multiply existing torque on one axle by some factor and transfer it to the other axle. The key is that there has to be some small amount of torque present or else 0 x 0 = 0.

Xdrive uses electronically activated clutches to engage the center diff, thus being able to transfer 100% of the torque to either axle even in 100% slip conditions. Is it better than a torsen system? In the extremely unlikely event (and by that I mean impossible) that you have ZERO traction on BOTH wheels of an axle, then yes xdrive is superior. The fact that it uses sensors means it should be able to "detect" slippage before lost of traction as well is another advantage.

What's really more important is the traction between wheels on each axle. Most of these cars with open diffs and traction control will brake the spinning wheel to transfer torque across the axle. My guess during this test was that they disabled that for the Audi and left it enabled on the BMW.

If you want a true performance AWD system look at a WRX STI. An adjustable viscous coupling center diff, which while slower to react can transmit torque in complete no slip situations, and torsen diffs on the front and back (pre 2011).

Honestly, I think actual awd performance for quattro vs xdrive has more to do with how the DSC is programmed for same axle traction instead of how the power gets to each axle.

I am not sure if that Audi use Torsen. Some quattro just like VW 4motion are using Haldex clutch too. What I believe the real trick is which wheel is touching the ground.

Audi's Quattro's major axle is front axle while BMW xDrive's major axle is rear axle. Torque are distributed to the other side as controlled by the clutch. If it was the front wheel that is touching the ground, the result is probably the reversed.

[mkoesel]

Give it time and we may see AWD passenger car sales pass RWD passenger car sales. Actually, I say that without knowing the current numbers and how things break down. I imagine BMW still sells more RWD passenger cars than they do AWD ones, but I'll bet it is closer than one might think. Ignoring two seaters, which are generally not targeting all-climate, year-round driving, there are few RWD cars now that do not have an AWD option. Looking at RWD sedans in particular, optional AWD is quickly becoming the price of entry if you want to be competitive. In another decade and RWD-only sedans could be extinct, and RWD-only four or five seat coupes could be limited to muscle cars and a couple outliers.

Originally Posted by bigjae1976

Exactly, BMW does not market xDrive as a performance attribute like Audi does.

I'm willing to guess that it would really send the BMW RWD "purists" over the edge. The M division is apparently toying with an AWD M5...rather reluctantly. Could you imagine the uproar and AWD M3/4 would cause? Look at what's happening with turbo engines.

[ORIGIN M.]

Originally Posted by ///S65

"The most technically advanced all wheel drive system" wow that's a big claim. Quattro seems more advanced to me though.

Quattro is overrated.

[Richi0303]

it says "private video". Can you make it public?

[snowyf31]

I've driven both an Audi S4 Quattro and a BMW 328i xDrive in the snow. The Audi had snow tires and the BMW did not. I must say, the BMW did quite better than I expected; it was very resistant to slippage. I've also driven Subaru's with snow tires in the snow as well. I must say that if the BMW had snow tires, it would definitely do better than Audi Quattro but in a test between a BMW with all seasons and an Audi with winter specific tires, the Audi does handle better.

[Glina]

Originally Posted by ///S65

"The most technically advanced all wheel drive system" wow that's a big claim. Quattro seems more advanced to me though.

Quattro sucks. I owned BMW X6 and Audi Q7. X6 was much better in snow with summer tires than Q7 with all weather tires.

[FilipMPower]

I just read a review, where the reviewer mentioned a 435i xDrive would understeer in almost every corner. Well, Im sure that wont happen in the M AWD, but can this issue not be resolved in the normal BMWs???

[JustChris]

Originally Posted by Dackelone

Did you know that BMW sells more xDrive models per year, than Audi does it's Quattro models! Audi just markets it's Quattro system better than BMW does.

Dack

Really, wow I for one was suckered by the Audi marketing, nice one BMW.

[SilentAttack]

Private

[BPMSport]

Originally Posted by SilentAttack

Private

+1 :/

[Hellkite]

Why even bother posting a video on a forum and make it private

[Powaup]

Originally Posted by jmcphillips1

How advanced does it seem here?

wow.... I really thought audi quattro was king, I don't think I could buy a passenger audi quattro after watching this video

[mkoesel]

Originally Posted by FilipMPower

I just read a review, where the reviewer mentioned a 435i xDrive would understeer in almost every corner. Well, Im sure that wont happen in the M AWD, but can this issue not be resolved in the normal BMWs???

It could, but the general public is afraid of understeer. Well, that may not be totally fair - they are perhaps just not accustomed to it. You see, since most passenger cars are FWD, people moving up to a luxury car with RWD may not be familiar with it's driving dynamics. Therefore, to make luxury cars more friendly to such people - who represent a large number of buyers, many of whom would not even be interested in buying the car if it were RWD - AWD cars are often purposely made to handle more like FWD cars (or at the very least, are made not to oversteer like a RWD car would).

[///Mposter]

Originally Posted by The long haul

Some say....
It makes hooning your SO M4 much safer after cars and coffee.

:

[ORIGIN M.]

Originally Posted by Gonven

Nice explanation about xDrive system

Please fix your video otherwise your thread is dead /

[indya8]

Originally Posted by jmcphillips1

How advanced does it seem here?

Loool thats a Bmw dealer bro... You're actually going to believe that?

[ORIGIN M.]

Originally Posted by smithe90

I have the little audio clip at the end as my text-tone

Awesome for you.

[zipphreak]