# xDrive versus old/current AWD system



## Magna (Jan 4, 2002)

Don't much about the engineering of the 2 systems. I assume xDrive must be better since it's the new system, but is xDrive better than the old AWD in every way? Are there some circumstances in which the old/current AWD is better than xDrive?


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## autobahn (Jul 12, 2003)

I have a 330xi and assume that the current AWD favors a more RWD feel while still giving you the benefit of AWD. The new system will probably be less of a RWD feel, but probably better for snow, etc.


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## TheXMan (Dec 17, 2003)

Magna said:


> Don't much about the engineering of the 2 systems. I assume xDrive must be better since it's the new system, but is xDrive better than the old AWD in every way? Are there some circumstances in which the old/current AWD is better than xDrive?


xDrive provides curve handling well. If the SAV is over-steered or under-steered then the feature automatically kicked in to adjust over/under steering situation. Also, in the snow driving condition, each tire is independently controlled for better control.


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## ChadS (Jan 4, 2002)

autobahn said:


> I have a 330xi and assume that the current AWD favors a more RWD feel while still giving you the benefit of AWD. The new system will probably be less of a RWD feel, but probably better for snow, etc.


Actually in back to back driving of an '03 X5 and my sister's '04 X5 the '04 with xDrive had more of a rear wheel drive feel to it than the '03.


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## Andy (Jul 16, 2003)

TheXMan said:


> xDrive provides curve handling well. If the SAV is over-steered or under-steered then the feature automatically kicked in to adjust over/under steering situation. Also, in the snow driving condition, each tire is independently controlled for better control.


Wouldn't the DCS just take care of this?



autobahn said:


> I have a 330xi and assume that the current AWD favors a more RWD feel while still giving you the benefit of AWD. The new system will probably be less of a RWD feel, but probably better for snow, etc.


My understanding of the xDrive is completely opposite. My understanding is that the xDrive works just like RWD, but the moment it senses a loss of traction the AWD would kick in, once stabilized, automatically go back to RWD. You kind of get the best of both worlds.

I have not read up much on the xDrive so I don't know a lot about it... so I too am interested in seeing a comparison of the two systems.

: popcorn:


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## jaisonline (Mar 24, 2002)

Magna said:


> Don't much about the engineering of the 2 systems. I assume xDrive must be better since it's the new system, but is xDrive better than the old AWD in every way? Are there some circumstances in which the old/current AWD is better than xDrive?


lets all stay on topic here and not get into the how much power goes to the rear wheels when driving on dry roads.

MAGNA, here's my 2 cents. it's all relative. x-drive, quattro, nissan's new ATTESA E-TS, benz's awd, and the awd system on my current 3-series.

i've driven all types of wheel drive/awd trucks and cars for a few years now. a change in engineering or the AWD approach of an existing system isn't going to make all that much of a difference UNLESS your comparing awd systems from different decades.

u know what makes the TRUE difference in awd systems? decent all weather tires, ground clearance, and DEFENSIVE DRIVING ABILITY. my leased '00 ford explorer was great in the snow with the part-time 4x4. then i bought the bmw and that's only slightly better (even w/ all the extra traction control/DHC/DSC/bla, blah blah than the explorer? why? because the explorer had truck tires and much higher ground clearance.

i will say one thing which is off-topic but i don't need any responses because i don't want to fill this post defending my or offending any opinions/feelings. i don't understang these XI owners who get their cars lowered. it defeats the purpose of having the extra inch of ground clearance for snow driving. u know... if my bmw had more ground clearance, i would never have to shovel the car out of a parking space (which i even rarely have to do now because the awd system works like a charm).


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## bmw325 (Dec 19, 2001)

The old system was a fixed split f/r. The xDrive (which is not yet available in the e46 xi btw), is basically a computer controlled differential that can -- its kind of similar to the quattro system in the Audi TT (but not the a4, a6, a8 which use the traditional torsen cetner diff). Because a computer controls the power application, it can do so under all sorts of different conditions-- where a purely mechanical system (like the torsen in the a4,a6,a8) cannot. I know one thing it does is to augment the DSC capabilities to control understeer and oversteering in turns. I believe it can send 100% to either end if it needs to.


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## autobahn (Jul 12, 2003)

jaisonline said:


> . my leased '00 ford explorer was great in the snow with the part-time 4x4.


My only comment on part-time 4x4 is it is never there when you want it on the road. I had a Jeep with part-time that could not be run on a dry surface. The wheels had to slip. It was useless on roads that were mixed dry and snow or with some ice. I love that the 330xi if full-time AWD. Do not have to be turning it on and off.


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## Kaz (Dec 21, 2001)

Um, are we trying to compare xDrive to the X5's old fixed-torque-split (38/62, I think) or the E46's system (don't recall the details but pretty primitive IIRC). From what I've read, xDrive seems to offer some significant improvements over both. If it didn't, I wouldn't think that BMW would bother retrofitting it to the X5.


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## bmw325 (Dec 19, 2001)

Kaz said:


> Um, are we trying to compare xDrive to the X5's old fixed-torque-split (38/62, I think) or the E46's system (don't recall the details but pretty primitive IIRC). From what I've read, xDrive seems to offer some significant improvements over both. If it didn't, I wouldn't think that BMW would bother retrofitting it to the X5.


e46 system is exactly the same as the old x5 system. It is indeed pretty basic-- fixed torque split and an open center diff-- just uses the brakes to re-apportion power. I wonder why they didn't upgrade the e46 xi to use xdrive as well?


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## Magna (Jan 4, 2002)

so if you want a car with AWD which would you go with? Audi's system which has to sense a slip then turn on, or xDrive which sounds like via computer "anticipates" slip then re-approportions power, or the fix 68/38 system of the xi.

BMW retrofitted the X5 with xDrive, why wouldn't they retrofit the xi's? perhaps because the xi's (E46) is in its last year of production?

from my reading of the above posts it sounds like xDrive is better than the xi AWD system, but the difference isn't a big deal in the real world. 

when would xDrive shine over the xi system? i think one poster said the xDrive is better in turns


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## jaisonline (Mar 24, 2002)

Magna said:


> so if you want a car with AWD which would you go with? Audi's system which has to sense a slip then turn on, or xDrive which sounds like via computer "anticipates" slip then re-approportions power, or the fix 68/38 system of the xi.
> 
> BMW retrofitted the X5 with xDrive, why wouldn't they retrofit the xi's? perhaps because the xi's (E46) is in its last year of production?
> 
> ...


magna,

i don't mean to offend but aren't you taking this difference in awd systems a little too seriously.

i don't care if u ride in a 1990s audi with their prev awd system, any awd system will perform good in snow and on ice AS LONG as you have decent tires, ground clearance, and your driving habits. a good example is the awd audi s4 with the standard tires. the awd system doesn't help a lick in snow because of the high performance tires. i know this because i have friends with the a4 and s4. the s4 owner couldn't even drive the car in the rain. plus i have the current 3-series awd system and it works great and slices right through ice/snow/rain.

buy the car you like for its overall features. all because audi "may" have a better awd system doesn't make it a better overall car than bmw and volvo cars with awd. i'm telling u from personal experience, awd systems are very similiar with just a few technology differences/enhancements; on paper they may look greatly different but when you're in the car driving, the differences aren't that big.


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## Magna (Jan 4, 2002)

jaisonline said:


> magna,
> 
> i don't mean to offend but aren't you taking this difference in awd systems a little too seriously.
> 
> ...


hi jais, no offense taken  glad to hear that it doesn't matter much, because i was getting serious over the x3 and audi a4, over the 325xi. it's been written the xi system is simple/primitive, but then again many posts tell stories how well the xi works in snow.


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## Nick325xiT 5spd (Dec 24, 2001)

The problem with the xi system is that it isn't primitive enough.

What it needs is at least one limited slip diff and none of that DSC/ADB bullshit.


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## Desertnate (Mar 11, 2002)

Magna said:


> so if you want a car with AWD which would you go with? Audi's system which has to sense a slip then turn on, or xDrive which sounds like via computer "anticipates" slip then re-approportions power, or the fix 68/38 system of the xi.


Just so you know...Audi had two seperate AWD systems. One that is in the A6 and A8 and is the original Quattro idea and other is the system in the TT, A3 and A4 (I believe)

The system in the smaller cars does wait for some slippage before kicking in (vicious coupling I believe or a Haldex type system with electronic clutches). The version on the larger cars is a full time system with a series of gears that constatly adjusts power delivery to the four wheels based on traction in real-time


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## jaisonline (Mar 24, 2002)

Magna said:


> hi jais, no offense taken  glad to hear that it doesn't matter much, because i was getting serious over the x3 and audi a4, over the 325xi. it's been written the xi system is simple/primitive, but then again many posts tell stories how well the xi works in snow.


magna,

cool. all i know is that my 325xi drives through everything except the highest of snow drifts because of the low ground clearance despite "having an awd system which is considrered overly simple or primative by people on this forum".

in my opinion, i wouldn't buy a car (e.g. x3) within it's 1st two year run because of production/quality issues. a rule of thumb is to wait 1-2 years until the kinks/gremlins are worked out.

the a4 is a great car for the money. i would have bought the 1.8t quattro over the bmw in /02 if audi offered power seats on that a4 trim. i couldn't bring myself to buying a $30k car w/o power seats. small thing i know, but it's like buying a luxury car w/o a moonroof. yeah, it's not needed but it's considrered a given feature on certain cars.

the x3 is an interesting vehicle. i haven't seen it in person yet though. i just wished bmw didn't outsource the production (may not be a big deal) and didn't use cheap looking gray-black matte plastic bumpers. however, if you're in the market for a smallish suv-go for the x3. i love the fact you get car-like gas mileage and suv rear cargo space.  i can't fit anything big in my car (e.g. 19-24" tv in its box because of the narrow trunk and rear door openings.).


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## bmw325 (Dec 19, 2001)

Desertnate said:


> Just so you know...Audi had two seperate AWD systems. One that is in the A6 and A8 and is the original Quattro idea and other is the system in the TT, A3 and A4 (I believe)
> 
> The system in the smaller cars does wait for some slippage before kicking in (vicious coupling I believe or a Haldex type system with electronic clutches). The version on the larger cars is a full time system with a series of gears that constatly adjusts power delivery to the four wheels based on traction in real-time


The A4 also has the "original QUattro idea" which utlizes a torsen center differential-- which is purely mechanical. As of the introduction of the 1st-gen A4, power from side to side is distributed using the brakes. By default, this differential splits the power 50/50-- and can distribute up 70% to either end.

All of the Golf based cars that have AWD (TT, A3, Golf, Jetta, etc) use the haldex center differential. Its computer controlled-- and can be setup to evenly distribute power to both axles in varying amounts as its "default" and it can re-apportion the distribution as necessary (up to 100% to either end) THe newer Volvo AWD systems also use a Haldex center diff I believe. The xdrive is similar in concept to the haldex-- I think its setup w/ a default distribution of probably something like 30/70 F/R but can re-apportion up to 100% to either axle.


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