Is BMW xDrive really better than Audi Quattro? From this video, it seems that the xDrive is a better All-Wheel system.

http://video.google.com/videoplay?docid=9072883197544018466

Quattro is "built in" whereas Xdrive is like a dealer-added option.

My BMW only has 3k miles and I hate it, I cannot wait to get back into an Audi.

<ul><li><a href="http://www.youtube.com/watch?v=0-FLbgL7KKQ">http://www.youtube.com/watch?v=0-FLbgL7KKQ</a</li></ul>

ESP was turned off on the A8 so that the rear wheels would slip and no power transferred to the front diff.

Real world: Quattro would eat xDrive's lunch.

HAHA! Proof that quattro eats xdrive for lunch. BWAHAHAHAHA. I knew quattro was awesome, not to mention cars equipped with quattro seem to suffer a lower fuel-economy loss than cars with xdrive.

The AoA websitae describes the A8 as having a "torque sensing" center differential, which has meant a mechanical Torsen differential in the past. Even with the ESP switched off, with a fixed-split mechanical differential splitting power between the front and the rear what happened in the video shouldn't be possible. The only way that should be possible is with an open center differential depending on the traction control to determine the front/rear torque split.

Anyone know if the B8 still retains the Torsen center? I recall the B6 had a Torsen center and open front/rear differentials. AoA only says "Self-locking center differential, automatic front to rear power proportioning, rear biased 40% front 60% rear". That statement would lead me to believe that they might've done away with the Torsen center in favor of a fully computer controlled (via the traction control) open differential layout for cost and weight reasons.

I've driven several AWD and 4X4 vehicles over the years. I live in "snow country" up here, and frequently have to be out on snow covered or icy roads. I don't drive AWD cars for any handling benefits, I drive them because they keep me on the road during our long winter season.

Based on my personal experience, and two winter driving schools I attended, I have yet to see any AWD car that can outperform the Audi Quattro system. Good handling, excellent control on slick surfaces, and truly exceptional gas mileage, have led me to my third Audi....an incoming B8 sedan Premium Plus.

BTW, in Premium or Premium Plus trim, I found the Audi pricing very competetive with the competition. The lease rates I've been quoted are close to what I had in my 2006 A4, albeit not quite as good, and not out of line with other brands.

<ul><li><a href="http://www.autozine.org/technical_school/traction/tech_traction_4wd.htm">&gt;Click&lt;</a></li></ul>

The link provided did offer a good, but somewhat dated, overview of AWD. For instance, there is no mention of Audi's quattro system's recent (2 years, as I recall) new technical feature: torque vectoring.

In a nutshell, quattro (TorSen, not Haldex) has evolved over the years from 50:50 nominal F/R power split (to 40:60) and, a couple years ago added Left:Right power allocation (like Honda's SH-AWD) thus providing the benefits Acura has been touting (and has been written about.)

At this point, not all TorSen equipped Audis employ torque vectoring (TV) -- one can assume the rollout of TV will happen like rear biased quattro -- over time.

In any case, TorSen quattro is "the best" -- but, after some two dozen plus Audi quattros and three X drive BMW's, I must hasten to add, these systems (in day in day out driving, not on the track, that is) both provide significant advantages on both high and low coefficient of friction surfaces.

If I had to pick one -- well, it would be quattro. But, we have a new 2008 X3 (that replaced a 2005 X3) and I have found BMW's AWD to be very competent, year 'round.

My upcoming A4 (with 19" sport package) will, undoubtedly be even more competent than my current '05 A6 quattro -- but I hasten to add, the X3 does have an advantage on our one or two days per year of deep, unplowed, snow -- due simply to its ground clearance.

The video that started this, however, is, er, "a lie" -- quatrro rules.

Yeah, the B8 has a gen III torsen differential that uses a planetary gear system so it's ideal for non-50/50 torque splits. As for the rear differential, no idea, but the center is still a TorSen.

Not to mention you can modify the quattro system with upgrades parts from companies like Stasis.

The Torsen center diff creates a 'tug of war' between the front and rear axles and is constantly changing based on conditions. The 50:50 or 40:60 split really only occurs on a flat smooth surface and a steady speed. Any other time, the axles are 'fighting' for the torque with torque being reapportioned constantly. The real split is constantly changing depending on conditions (39:62, 55:45, etc.) and is seamless and unnoticeable.

This is why people refer to Torsen quattro as being a "proactive" system rather than "reactive." Unlike most AWD systems, Torsen does not need to detect actual wheelspin to shift torque, as torque to transferred instaneously if wheelspin starts to occur (not after it is detected as in X-Drive).

The maximum amount of torque that can be apportioned to an axle depends on the bias ratio of the torsen unit. Audi currently uses a bias ratio of 2:1. This means that up to 66% of the engine's torque can go to either axle. In the case of the 40:60 split, it also means that more of that maximum torque goes to the rear than shifted to the front.

The early torsen quattro systems used a higher bias ratio to allow more torque shifting (Stasis also sells a 4:1 high bias unit) but Audi discontinued this due to customer complaints of binding (such as in tight turns). Audi lowered the bias ratio to 2:1 for its road cars to still allow some torque transfer but also address customer complaints and lack of understanding of the system.

Personally, I like the higher bias ratio (4:1) as evidenced by my installation of the Stasis modified torsen differential. A 4:1 bias ratio allows much more torque to go front or rear, almost 90%(!). I really notice a difference on track days when I want to power out of a turn and the unit can transfer almost all of the V8's torque (if necessary) to the rear to push me out of the turn (like a RWD car). It makes more of the engine's torque usable and flexible in my opinion. But I'm biased, of course (ha, ha).

On a final note, the torque-vectoring system Audi has developed will debut on the B8 S4 intially. It will not be a standard item but will be optional.

Hope this helps clarify...

I had a 1998 Audi A4 2.8 Quattro/Tip/Bose and now drive a 2006 BMW X3 3.0i manual/sport/premium/etc. So, from my experience:

Quattro is more seamless, integrated, and just totally transparent to the driver. But, xDrive gets the job done. Here's one example: Making a sharp left across traffic in the rain in my X3, I popped the clutch too aggressively and was able to get the left rear wheel to spin a bit before the AWD system reined it in. I was never in any danger and it was a non issue. That said, nothing like that had ever happened to me in my Audi A4.

I went over to BMW for two reasons: I can get any car I want with a manual transmission and the in-line six-cylinder engines revs so incredibly smoothly! My X3 is perfect for me here in the Pacific Northwest: it's a fun, engaging drive on the highways and windy mountain roads, and it has enough ground clearance to get me to all of my favorite trailheads.

Here's a photo from the trailhead to Mt Aix, over Chinook Pass near Yakima, WA:
<img src="http://home.comcast.net/~jrdailey/x3ext.jpg">

And a photo of my old Audi A4:
<img src="http://home.comcast.net/~jrdailey/Olympics/files/page7-1000-full.jpg">

If you see my post above, I've owned both and just don't think this is that big a deal. I agree that Quattro seems more integrated, but I didn't think the difference was huge.
What about your xDrive experience has been so devastatingly bad? Can you give us a little color? What kind of BMW do you own?

Thanks!

quattro has moved on quite a bit since your B5. I think the best way to describe them is that quattro is active while xDrive is reactive.

I said that Quattro is very well integrated and transparent to the user. It's the better system of the two. If it has gotten even better since then, great!
For my needs, xDrive gets the job done and the X3 is a better package for me overall.

Also, I regularly drive my parents' 2003 Allroad 4.2Quattro, 1990 A8 Quattro, and 2005 A4 Quattro cabriolet. So, I've definitely stayed current on Audi's offerings.

I'm not sure why you thought you were disagreeing with me...

just that the new quattro is substantially different than the one in the B5 so I thought that is not an up-to-date comparison. With the introduction of torque vectoring in the S4, it is going to be even better.

Sorry if I was not clearer in the previous post.