Opinions of the all-wheel BMW varient?
Posted by Earendil
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For my second BMW musings post of the week, I'd love to hear what people think of the ix/xi/all wheel drive BMW.
I love bimmers (dur) but I also live in the Northwest of the US, and as such entertain driving on snow/ice frequently enough to think it's fun. Now, there is nothing quiet like driving a rear wheel light car in the snow/ice, and as fun as it is, sometimes you just want to get someplace, and every so often rear wheel drive makes this not dangerous, but physically impossible. So I've tossed around the notion of having the next bimmer in my life be all-wheel, and being a half-way intelligent human went to do some researching. It would appear that BMW is not known for their ix models (surprise surprise). Every review I've found so far, of any BMW over the 3 series generations, makes a sidelong mention that the all wheel drive variant exists and nothing more. It's certainly nothing BMW brags about, and reviewers seem to ignore. So Peter has one in E30 flavor, and Cab has one of the E46. Perhaps at least you two have been more keen to the pros/cons of the BMW all-wheel drive systems and whether they get the job done well? Anyone else have an opinion? Do they serve well as snow vehicles? Or is this an option for someone who can't stand to buy anything but BMW, and if one actually wants an all wheel drive sedan they should definitely look elsewhere? ----------------------------------------------------------------------------------- 1989 - E30 - M20 - Manual. Approximately 270,000 miles 2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles 
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I'll get back to you in more detail tomorrow. Short answer: for winter driving, my ideal setup is snow tires with RWD and LSD. That gives you independent control over both ends of the car.
In my experience, the AWD, at least the E46 version, gives you some advantage in some situations, but the combination of DSC and open differentials takes a lot of the control away from the driver, and that can be very disconcerting. I am not a fan, and if we could have found a 325iT, that would have been my first choice. However, it being primarily the wife/family car, I think the advantage in the limited situations is okay. We still use winter tires, and I would not consider living anywhere with any kind of serious winter without proper tires. Also, having winter tires allows you to run real summer tires in the warm weather. Cab 
1990 325i(s) 2004 325XiT |
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tyler,
i know how you feel regarding the wanting to drive in the snow/ice in the PNW. i am so tempted to buy a set of winter tires for my car just for the 2-3 days where they would come in handy (although last winter it was about 2 weeks!). i have always read/heard that the audi quattro systems are better than pretty much any other AWD system. i suppose subaru stacks up pretty well, too. with that said, i doubt the BMW awd systems are "bad", they just don't have the same legacy as the other companies because it isn't their primary focus. obviously the xi setups are better than the ix setup, as well. as for driving in the snow with an LSD... i did it once back in december, and promptly got stuck. i also had 225/40-16 UHP summer tires. maybe if i had 195/something-16 then it wouldve gone a little better, and obviously if i had winter tread or even all season tread, i probably could've gotten up the 1 degree incline i was facing.  
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You just had to go and start that sentance with "obviously" didn't you. I've attempted to find some sort of article describing the all wheel drive iterations BMW has gone through, but all I can really find is BMW's own info on the current system. What's the difference between the 'ix' and 'xi', besides that one is the newer badge?
Well, I intend to live in or around Seattle, so the need to actually drive in snow will be chosen. That said, I love my winter sports and so often times choose of my own free will to drive up long, steep, snow covered inclines. This also puts one in the position of pissing off a bunch of people on their day off if you put your car sideways in the road ;-) Proper tires and weight are the other 2 sides to the three headed snow driving monster, and should be respected. But there is just something to be said about vehicles who have all contact points with the ground attempting to roll forward, as opposed to 2 contact points attempting to shove two other points through the snow. ----------------------------------------------------------------------------------- 1989 - E30 - M20 - Manual. Approximately 270,000 miles 2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles
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The E30 iX was the last BMW that had real mechanical AWD with mechanical torque portioning. Everything after it was computer controlled and the torque was transferred by applying brakes to the wheels
This site has all the info you need to know about the 325iX. You will not find a better snow mobile than this...the Audi doesn't come even close. You have to wonder why the E30 iX cars were banned from certain types of racing 
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something tells me that a new 328xi would handle much, much better than an e30 325ix, regardless of how the AWD system is controlled.
Edited 1 time(s). Last edit at 07/22/2009 09:17PM by daniel. |
Like Tyler said, don't be so free throwing around that "obviously." The newer versions are more technologically advanced, true, but that doesn't necessarily mean better.
As I hope you realize, getting stuck in that situation had nothing to do with LSD and everything to do with summer tires. Tires are the single most important variable when considering winter driving, at least for normal people doing normal driving. I don't live in Norway or Alaska, but we get pretty decent winters in New England, so after 10 years here with various different cars, I have some experience. I've driven FWD, RWD, and AWD at various times, all with both winter and all-season tires. I've never attempted to drive in winter conditions with summer tires. The only time I've ever been really stuck was when I was in a VR6 Jetta with wider-than-stock and fairly close to being worn out all-season tires. There have been other times when I've had to rock back and forth a couple of times or be very gentle with the driver inputs, but I've only truly gotten stuck that one time. And even then, part of the reason I was stuck so long was because traffic kept coming along (and not stopping to help) and I would have to stop trying to get unstuck and wait for them to pass. I have never, with any drivetrain, even felt the slightest bit out of control when I was using the proper tires. The popular opinion (and just b/c it's popular doesn't make it correct) is that AWD is the bestest way to go. However, so many of those people think that b/c they have AWD, they don't need winter tires, and that their car's technology will save their butts in bad conditions, so they continue to drive through snow and ice as if it's a bright and warm summer day. No matter what you're driving or equipped with, the nut behind the wheel remains the most important piece of hardware in the vehicle. However, this popular opinion leads people who don't think much of driving to come to the simple conclusion of "I live where it snows, I therefore need a big SUV, and then I don't have to worry about anything." IMO, that's the worst type of vehicle for the majority of drivers, simply due to the large mass of the trucks and what physics says will happen to things with large mass moving on slippery surfaces. The larger, heavier, higher center of mass car is already much harder and takes longer distances to stop than "normal" cars, and this gets significantly worse in winter. They'd be better off in a lighter vehicle with snow tires. But you'll never convince the masses of that. If you really need to get through deep stuff frequently, then you might really need the high ground clearance of a truck/SUV. But in reality, that doesn't apply to nearly as many people as actually own the dang things. The exact type of driving you do is very important to consider. If you live 10 miles down an un-plowed private road, your needs are vastly different than mine. The only time I ever really need to push on when the conditions are terrible is if I'm already on the road when the blizzard starts. And even then, a well-equipped area will have plows and sand/salt trucks out on the roads quickly. If it snows 2 feet overnight, I will stay at home until the plows get the road cleared, so for the most part, driving through deep snow is not a common thing I have to deal with in the winter. That's why my winter tires for both of our vehicles are not deep snow tires, but tires that are designed more for mostly cleared roads where you might encounter ice, patches of snow, cold temperatures, and only occasionally have to get through the deep stuff. I have Blizzak WS-50 tires for my E30, and those are awesome in deep snow, but get very wobbly-feeling and mushy on dry/cleared roads when the temp gets even a tiny bit over the freezing mark. Our current winter tires are Dunlop Wintersport, on both of our cars. We've had them for 4 and 3 winters on the E46 and Mazda3. No problems ever encountered with them on. I like them and would get them again, definitely. But if you are on the road in bad conditions, just go slowly and carefully, and don't worry about what other drivers think. Yes, I get annoyed when I'm toodling along with winter tires, driving appropriately and safely for the conditions and I get stuck behind someone going 10mph, but I'd much rather that driver go really slow and hold me up than feel pushed by me and drive too fast and wreck. So I pass if I safely can, otherwise I remain at least several car lengths behind and try not to get too frustrated. My favorite setup for winter, as I mentioned, is RWD with LSD and winter tires. This allows you to control the front end of the car with the brakes and steering wheel without any torque applied by the engine, and the rear of the car with the gas pedal. LSD keeps both wheels spinning when you're on glare ice (or only one wheel is getting minimal traction). AWD will help you get moving from a dead stop, and sometimes that's quite handy. But I've always thought that if the conditions are so poor that you really can't get moving (especially with the right tires), then maybe you should hang out and wait a while because if you can't get moving, you probably can't turn or stop very well either. That's not always possible or practical, so sometimes AWD really helps you out. But I contend, and my experience backs this up, that if you have any power going to the front wheels, and it's slippery, that only hurts you when you're turning. A non-powered wheel has a better chance of making use of whatever limited traction is available to turn the car. If you apply any torque to those wheels, that limits the amount of traction the tires can use to change direction and makes the tires spin, and a spinning tire when you're turning means that you're not turning anymore and you go straight through the corner, even though your wheels are at full lock. For braking, it doesn't matter one bit what your drivetrain is, the only thing that matters is tires and weight distribution of your vehicle. This is what is behind the concept of the "traction circle." There's a limited amount of traction available between a given surface and a tire. You can use 100% of traction for braking or turning or propulsion, or some combination that adds up to 100%. Use some of it for propulsion and you can't use that amount for turning. Likewise with braking. Braking in a straight line is easier than braking while turning. So I prefer to use none of the available traction to the front wheels for propulsion, because it allows me to use more for turning and braking. Unfortunately, I'm not driving any RWD cars at the moment, so I have to make do with what I have. So anyway, this is why I've gotten into countless discussions with people around here who insist that AWD (with all-season tires) is the best/safest/only way to go in the winter. The fact is, many or most of these people think that the car will save them and they can carry on driving like they do in the warm weather, one hand on their cell phone, drinking coffee, and feeling superior to all the lowly and stupid RWD car owners.  Cab
1990 325i(s) 2004 325XiT |
Not necessarily. The E30 iX uses, as Archie said, a pure mechanical system for apportioning torque. xDrive is totally different, and while it is advanced, it's not necessarily better all the time. Plus, the electronic controls are more prone to failure (or needing a reboot) than a mechanical system. You usually know when a mechanical system is wearing down and needs maintenance (or has already failed) but you often get no warning at all with an electronic system like they currently have. They're good cars, don't get me wrong, but don't be so quick to unequivocally state that the new car is much better. Cab
1990 325i(s) 2004 325XiT |
The E30 iX is a pure mechanical system (not sure if there is also LSD in front or rear or both) that splits torque 32/68 (or 38/62, I don't remember) F/R. The newer systems also have electronic controls. My E46 xi is NOT the same as the current xi cars. I also have a fixed mechanical torque split, however there is also some brake-based control to mimic a mechanical LSD. It also has some electronically controlled braking applied to the center differential to somewhat control front to rear torque split, but the actual split does not change. The current xDrive system does actually vary the torque going to individual wheels. How, I'm not really sure, but I know it is different than both the E30 and E46 systems (which are actually very similar to each other). My biggest problem is with DSC. You must have it enabled in order to have "LSD." If you disable it and you're trying to start moving on ice (like when I took the E46 ice racing), then the car just has open differentials and one wheel spins happily and the car doesn't move. If you have it enabled, as soon as the car begins to slip, it cuts your engine power until the car is stable again. So, when I was ice racing, I'd have DSC on in order to start moving. Once I was moving, and I started to turn, it would detect a slip, and I'd lose engine power until the car stopped moving. It happened more than once, I'd be sliding around a corner with no traction, I'd be headed towards a patch of snow where I knew I could get traction, but the car wouldn't give me any power and I'd slide right through that patch of traction and I couldn't move again until the car had totally stopped. Damned if you have it on, damned if you have it off. Ugh. I haven't driven an xDrive-equipped car, so I can't comment.
As I said in my long diatribe elsewhere, don't think twice about what other drivers think. Drive safely for the conditions, and the onus is on them to do the same. Get yourself to your destination safely, and don't put other people in danger. If the other person is following too closely and can't avoid you when/if you stuff your car, that's their fault. Not to say people don't drive inconsiderately and dangerously, but if that's the case and you have to push yourself beyond your safety limits, simply pull over and let them pass before continuing on your safe and merry way. Odds are you'll have to stop in a little bit and help pull them out of a snowbank, but at least they won't have wrecked your car as well as theirs.
Proper tires are the #1 issue. All cars have 4 wheels attempting to stop you, and all cars have 2 wheels attempting to turn you. Again as I said elsewhere, if the conditions are so bad that you can't get moving without AWD, then you may not be able to stop, and it might be best that you can't get moving. Get decent tires and don't worry about A/R/FWD. Any of them are safe with proper tires under most driving conditions. If you want to run a snowplow business or go rallying, you have different needs. But for getting to a ski resort or going ice racing, proper tires and a good head on your shoulders are the most important factors. Cab
1990 325i(s) 2004 325XiT |
well it depends how you define better, also. maybe it isn't as enjoyable to drive, but it is probably safer, and given the same tires the new version probably handles better, also. just because some of us enjoy the mechanical aspect of AWD and don't want traction control doesn't mean that it is going to handle conditions better than a newer version of AWD with more electronics. for ice racing i'm sure a consistent torque split with no interferences is preferred. yes i very much realize that, i just thought i'd share the story since it is kind of funny. and i think i remember reading that the iX front diff is open, not LS, but i'm sure Peter would know for sure.
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Agreed...better means something different to the guy who drives his cat than to someone who aims it. The modern systems have been developed to keep the average driver safe by taking over control of the car in slippery conditions. They do this far better than the older systems; but they also remove any chance the driver can actually 'drive' the car...all diver input is basically reduced to turning the steering wheel. For the most part, you are right about the A/F/RWD being much the same with proper tires. There are a few instances though that the F?RWD systems are seriousyl outpaced by AWD. I'll just list two. First is when you are going on that skiing trip and you get to those step hills where other cars have stopped and can't get going; the AWD(at least the iX) will allow you to not only get safely started but give you the sure footedness to drive around the other immobile and/or sliding vehicles. The other; as I experienced two winters ago; was when I was able to tow another car up a slippery icy hill. There were already several vehicles which had slid off the road into the ditch or onto peoples front lawns and became stuck. The car in front of me made it about a third of the way up the hill before it came to a stop. The driver was smart enough to realize that he would only end up in the ditch if he tried to proceed or attempted to back down the incline; the crown in the road had already dispatched a couple of cars that had tried that. Anyway, I stopped to see what he was going to do and he waved my around. I gently eased around him and when I was in front; stopped and backed up to about 10 feet in front of him than got out and went to see if he would like me to try and pull him up the hill. I have a short length of chain I usually keep in the trunk and hooked it to the tow eyes on the iX and the other car. I told the other driver that once he felt the pull to only give his throttle a little gas so his tires weren't spinning wildly. As soon as I took up the tension, we started moving forward and the iX did a great job of portioning torque to the slipping tires. Once under way, the tires no longer slipped and I had us to the crest of the hill in seconds. My tires...no season cheapos. The other car...a 740i. Admittedly, these are rare occasions but it's nice to know that the iX can get the job done 
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Yup, as I mentioned, getting moving in very slippery conditions is one of the conditions where AWD really helps. And I agree that in such a condition, it's a great thing to have. In my normal course of winter driving, it's never been an issue. Snow tires have always provided more than enough traction for all of my cars to get around with no problems. Cab
1990 325i(s) 2004 325XiT |
Yes, me too although one year I got the middle of my 2002 hung up on a snow bank with all four wheels hanging in the breeze (don't you hate it when that happens?). Luckily a near by pick-up truck had a rope and pulled me off  my kids, who were young and with me at the time, never let me forget that one!
Rick |
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Shoot, I go away on vacation for a week and miss a big discussion of one of my favorite cars, the 325iX. Most of what I would add to this discussion has already been said by others, but I'll just add a few observations of my own.
I live in ski country, I love to ski, and I can frequently be found in the winter months driving through snowstorms to get to the mountains, often before the plows are out. When I'm not doing that, I can be found sliding my car around at ice races or snow rallycrosses. Around home I'm frequently wallowing through 12 inches of snow or more in the driveway before the plow guy comes to plow us out. With all the snow driving I do, I maintain that the E30 325iX is one of the most perfect snow vehicles ever built. It's like the love child of a Jeep CJ and an E30. With good snow tires (which should really go without saying), it will go pretty much anywhere, be rock solid on snowcovered roads, and be fun to drive at the same time. There are not many cars about which that can be said.
(BTW, I agree that good winter tires are more important for snow travel than which wheels are powered. But I also insist that given good tires, AWD is better than FWD or RWD for predictability in slippery conditions, and staying on the road when they are slippery. In my garage I have one of each, and the AWD is easily the best driver in snow.) Audi and Subaru snobs can sometimes been found on the Internet espousing the superiority of their AWD systems over BMW's supposed iX kludge. Having owned an iX for several years now, I maintain that the AWD system is outstanding. The rear-biased torque split (63% R/ 37% F) is perfect, and more fun to drive than the 50/50 split found on most other AWD cars (or especially the *gag* 90/10 split found on Subaru automatics). BMW kept the standard E30 engine position engine mostly over and behind the front wheels, as opposed to Audi's hanging the engine out way in front of the front wheels, which creates significant understeer issues. If the trade-off to that is having the drive shaft pass through the oil pan, I'll live with that. It's not like I spend a lot of time dropping oil pans anyway. Most importantly with respect to the Audi comparison, I've known too many friends with Audis to ever consider owning one myself. At the risk of offending any Audi fans lurking around here, they're great cars, but horribly problematic. The BMW, while not in the same league as a typical Japanese car, is still comparatively bulletproof compared to a typical Audi. BMW only exported about 2800 iXs to North America from 1988-1991, and I would guess that about half of those are still running. Not bad for a 20-year old car with a supposedly second-rate AWD design. The main Achilles heel in the AWD system of the 325iX is the viscous coupling found in the center diff. If the car is ever towed with two wheels on the ground, the viscous coupling will be fried in very short order. If that happens, the car will still move, but the center diff will not lock, i.e. it will be open. Many of them have had this happen over the years. If you're shopping for an iX, you really should ascertain the condition of the center VC first, because if it's shot, it's about a $1000 fix. Having said that, if the VC is not abused, it will last indefinitely. Mine has 150K miles on it and is still strong. There is also a viscous coupling in the rear diff, but that is not subject to the same dangers as the center diff because most people aren't towing only one side of the car. The front diff is open, as it should be. As Cab has noted, this old-fashioned entirely mechanical system has proven its worth over the years. If it isn't as "sophisticated" as modern electronic systems, the long experience of happy iX owners has shown that perhaps sophistication is overrated.
I'll finish off with a few pics of my iX in its native habitat: 
 __________ Dave '91 325iX Edited 2 time(s). Last edit at 07/28/2009 07:56AM by Dave_G. |
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Dave, I was wondering where you were!
How does one check the center VC thingy, and what exactly does it do and what are the ramifications of it being hurt?? Thanks for all the great IX facts, love that car, hope you had a good holiday, ours got side tracked by two operations (on me) and one hospital stay but its all good now
Rick |
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haha those tests look... safe.
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