# AWD: BMW vs. Audi vs. Porsche vs. Subaru



## Magna (Jan 4, 2002)

I know each company designs their AWD differently but which car company makes the best one? Difficult question to answer, I know, and the different AWDs are designed for different purposes. For example, I can't imagine Porsche's AWD system in the 911 is designed for snow traction or off-roading, while the Subaru system probably is. Perhaps that's why the Subaru don't handle well.


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## Nick325xiT 5spd (Dec 24, 2001)

Why do you say the subarus don't handle well?

Put 17" wheels and real tires on a WRX and it handles beautifully.

And, BMW has the most primitive, least effective and worst handling system.


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## nate (Dec 24, 2001)

Nick325xiT 5spd said:


> *
> 
> And, BMW has the most primitive, least effective and worst handling system. *


Weren't you able to get up an icy hill on S-03s with that "ineffective" system? :dunno:


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## Nick325xiT 5spd (Dec 24, 2001)

I never said it was ineffective. I said it was the least effective and most primitive.

ADB-X shut off or became relatively ineffective numerous times while I was in the snow. Since when did you LIKE open diffs?


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## JonW (Jan 6, 2002)

Magna said:


> *I know each company designs their AWD differently but which car company makes the best one? Difficult question to answer, I know, and the different AWDs are designed for different purposes. For example, I can't imagine Porsche's AWD system in the 911 is designed for snow traction or off-roading, while the Subaru system probably is. Perhaps that's why the Subaru don't handle well. *


Here's my take on this: On paper, the Audi system is great. Wonderful design. The BMW design is relatively primative. But out in the real world, the BMW system is all you'll ever need. On a very steep hill of 15-20% grade with 5" of snow, I was able to make it up the hill with no problem. The DSC, etc. didn't even kick in unless I gunned it just to see if I could kick on the DSC. And I stopped in the middle of the hill and started right back up many times. The tires were Goodyear RS-A's. So it seems to me that the functionality of the BMW AWD system is great. The better design of the Audi system is only an academic difference.


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## Nick325xiT 5spd (Dec 24, 2001)

It is an academic difference into you start trying to corner under power. Then ADB-X kicks in and starts generating understeer.

BMW's system would be FANTASTIC, IMHO, if it had at least a rear LSD and NO ADB-X. I LIKE the transfer case. I don't really like it when systems start throwing the power around. But open diffs still CRIPPLE the system. Especially when you have the brakes kicking in under power.


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## HW (Dec 24, 2001)

checkout this site

4 wheel drive systems


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## FSelekler (Jan 15, 2002)

As you guessed it Magna, it is not an easy question to answer. The 4x4 systems are designed differently with several things in mind, the two most important ones being:

1- Purpose of the vehicle
2- Weight distribution of the vehicle

From a consumer's perspective, the question you need to answer first is how will you be using the vehicle? If you are looking in using it mostly on the street and objective being nimble through twisties that is one thing. If however, you will be going off-road occasionally at high-speed that is another thing. Then the real question is which car can you afford given the above situations?

All of the cars mentioned above, including the 911, will go off-road with proper chasis setup (a 911 TT won Pikes Peak this year in its class).

For example, in my situation, I would love to have a GT car that I can safely explorer the limits on road conditions. IMO, for me the 911 C4S is the perfect 4x4, but cannot afford it 

btw - I think the WRX really handles terrible on the road out-of-the-box, even with 17"ers. Very heavy understeer on entry and slight oversteer on exit. But then again, I probably did not know how to drive it too well.


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## Nick325xiT 5spd (Dec 24, 2001)

FlyingToaster said:


> *btw - I think the WRX really handles terrible on the road out-of-the-box, even with 17"ers. Very heavy understeer on entry and slight oversteer on exit. But then again, I probably did not know how to drive it too well. *


Ever drive an xi? I don't like the WRX because it's far too unrefined, the transmission isn't very good, and my feet are too big for the footwell. But it sure as hell outhandles my car.


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## nate (Dec 24, 2001)

Nick325xiT 5spd said:


> *Ever drive an xi? I don't like the WRX because it's far too unrefined, the transmission isn't very good, and my feet are too big for the footwell. But it sure as hell outhandles my car. *


<----

Thinks you should have gotten a 325iT :thumbup:


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## Jspeed (Dec 23, 2001)

Let me add my two cents. Open differential sucks! FWD, RWD, AWD, it doesn't matter. I bet the reason why Xi models can do relatively well w/ an open diff is b/c of the well balanced chassis of BMW's. If Audi's, w/ their 60:40 front/rear weight bias, didn't have a good LSD like the Torsen, it would not be half the car it is.


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## Nick325xiT 5spd (Dec 24, 2001)

nate328Ci said:


> *<----
> 
> Thinks you should have gotten a 325iT :thumbup: *


I think I've said that on a number of occasions.


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## nate (Dec 24, 2001)

Nick325xiT 5spd said:


> *I think I've said that on a number of occasions.  *


Maybe even the gorgous lines of the coupe


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## Nick325xiT 5spd (Dec 24, 2001)

nate328Ci said:


> *Maybe even the gorgous lines of the coupe
> 
> *


And I've strongly disagreed with that on quite a few more. If I get another Bimmer, it'll probably be a sedan for the larger engine... But I will never get a coupe.


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## nate (Dec 24, 2001)

Nick325xiT 5spd said:


> *And I've strongly disagreed with that on quite a few more. If I get another Bimmer, it'll probably be a sedan for the larger engine... But I will never get a coupe. *


yea, those big engined coupes really suck.


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## ·clyde· (Dec 26, 2001)

*Re: Re: Re: AWD: BMW vs. Audi vs. Porsche vs. Subaru*



DougDogs said:


> *I live in the real world, and the BMW system is not all I'll ever need. For winter weather, I miss my Quattro's *


Only having the one day a little while back to go on, the BMW system more than meets my needs (and truly exceeds them whne considering my tire situation). It may not be as good as Audi's quattro dunno:...never driven one in the muck), but that doesn't matter. It may not be as good in the dry as Audi's quattro dunno:...last quattro I drove was a 4000 about 15 years ago), but that doesn't really matter either: I don't drive at 10/10s on the street and 98% of the time on the road, I'm not losing a step to anyone or anything where power isn't an issue, and that's got nothing to do with the drive system.

The WRX I test drove was a lot more nimble than my xiT, on some twisties (and with 15% less weight, it damn well better be). I've held my own against the WRXs in the local autocrosses, but one mediocre driver vs another mediocre driver in another car is no way to judge anything.

I turned the 3rd FTD at an autox in the wet (and I left time on the course) with my xiT, so the system must be doing something right.


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## pdz (Nov 17, 2002)

*driven WRX & 325xiT at the track.*

i cannot comment on the C4S (996 chassis) as i have only driven it twice on sunny days, dry road. it probably is quite effective even with a viscous center diff because it's enough to be faster around the 'ring than the C2 (despite the weight penalty).

the 325xiT does not have enough power to speak clearly about the follies of the system to me. of course it understeers, but if you enter a corner with good speed, the car tracks beautifully and i can only imagine what a 330xi at the track is like. despite the weight, i would bet, properly setup, it would handle quite well, if only because of the rear bias. further, on icy roads (no snow to bog the car down) the xi system is more effective at locomotion from a standstill on a flat surface or on a hill because it limits wheelspin. does this system effectively get the car through up to 5 inches of snow? sure. not as efficiently as AWD with differentials, though.

the WRX does handle like a little pig on ice at times out of the box. it needs some serious tweaking. see the road&track this month where they compared OEM stock, STi suspended, and tommy kaira or something tuned. the lap times got better....and it was more due to suspension than to HP. would you handle well if you were shod with mushy RE92? ha ha ha ha. the WRX, unlike the xi, is pretty decent on the track, but like the last gen s4, you have to take a different line on the track because you know you've got some weight, a lot of push, and limited dry traction (can't really go too wide, even with spacers on either car). so you need to carry some serious momentum on a good line and power out...hopefully on the right line so you're not scrubbing speed because of understeer. i agree with the tendency to kick the tail out on exit, and this is probably due more to nonlinear power band exacerbating this tendency.

on ice, the WRX is pretty squirrely as the tires scrabble for power. now, the STi may be different as it will have a front LSD, too, but in its current form, the car takes longer to start moving than the xi on ice, flat or incline. in the thicker stuff, it does not seem all that superior to me, and this is kudos to bmw for the locked in center diff distribution of power, that is truly an asset (to me) because there is no surge as power gets moved around (try this with a volvo AWD vehicle and feel the jerkiness as it retorques around the power).

in low to mid speed situations, the WRX and the xi (i.e. autocross) suffer because of their handling and the xi needs LSDs to be effective. but at the track, i found the xi to handle really, really well; there were no slow turns where power overwhelms the traction, so i never missed an LSD.

hope this helps. i do not think porsche utilizes LSDs either, do they? they are, like bmw, believers in ABD's. at the end of the day, nothing beats snows, if that is the original question.


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## JonW (Jan 6, 2002)

*Re: Re: Re: AWD: BMW vs. Audi vs. Porsche vs. Subaru*



DougDogs said:


> *Not wanting to start a flame war, JonW, but I've been through, and worked in Indiana, and where is there ANY mountain with a 15-20% grade????? Having owned two Quattro cars before owning my current 325xi I can tell you that it is much more than an academic difference. The way the BMW 2 wheel drive system "tries" to transfer power, makes for much more driver interaction to try to keep the vehicle straight and under control than any quattro system does.
> 
> I live in the real world, and the BMW system is not all I'll ever need. For winter weather, I miss my Quattro's *


Hey Doug,

I actually live on such a hill, so being able to get up it well is pretty imporant to me. I know, it's Indiana- who would have guessed we have hills!  I'm in Lafayette and we have the Wabash River here. The river has carved out a good chunk of land over the eons, so much of the town either goes downhill toward the river or uphill away from it. Almost a mile on either side.

At any rate, you may be right about the Audi. I've never driven one in the snow. But last winter, I was really impressed with how well my BMW did getting up the hill in some snow. It couldn't have clawed its way up the hill any better than it did. So I get the impression that any better of an AWD system wouldn't add much to my being able to get home. But if you've owned both cars, you must certainly know. I would think that in flat out, driving at the edge performance, a better design would be an improvement. Although there's no question that from an engineering standpoint, the Audi design is much more elegant.


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## pdz (Nov 17, 2002)

*there is also practical elegance.*

the xi models are lighter than their audi counterparts by a good 200-250 pounds. and that is meaningful at the track or on the road.

there is also the issue of less mechanical wear and tear. differentials (LSDs) generate heat and need serious upkeep and repacking to deliver solid performance long term.

for practical utility and foul weather capability, i'm more than pleased with BMW's solution tot he problem. i'd much rather see rotors and pads replaced than layer over that LSDs changing out the fluid and having the gears rebuilt.

just my $0.02 of the practical elegance of the xi system. it is what it is and it is very effective in most situations when properly equipped with the correct tires.


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## brave1heart (Jan 7, 2002)

*Re: there is also practical elegance.*



pdz said:


> *the xi models are lighter than their audi counterparts by a good 200-250 pounds. and that is meaningful at the track or on the road. *


Not true. Our '01 A4 Q is 3,250 lbs. The '01 325xi was close to 3,500 lbs.


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