01-04-2013, 11:53 AM | #45 | |
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Today's week forecast for Vancouver (in the traditional coldest part of the winter) is yes for more rain and temperatures of about 7 degrees. |
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01-04-2013, 12:50 PM | #46 | |
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Small price to pay for the additional safety AWD provides. |
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01-04-2013, 01:19 PM | #47 | |
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So that's where the distinction comes in.
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01-04-2013, 02:28 PM | #48 | |
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Also - you can't say an Xdrive car pays for itself based on the cost of the tires. An AWD car with all seasons will be most price efficient, but won't handle as good as an RWD car with summer tires in the summer and dedicated winters - especially if you push your car towards the limits (which if you bought the 3 to be a sports sedan and not a luxury sedan, probably happens fairly oftne). It all depends on your driving habits...Audi made a pretty successful business out of selling AWD cars. I just care that the car is safe enough to get me home in bad weather, the wife has a truck for blizzards (no AWD is going to get you over the fact that the car only has a few real inches of ground clearance)
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01-04-2013, 03:57 PM | #49 | |
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AWD is not just for snow, it can help power a car thru a turn, it can help with traction in heavy rain and driving over large puddles. If you loss traction for whatever reason, it can recover faster than a RWD car. Where I am, it snows a lot more than 5 days a years. I guess if I live in an area where it only snow 5 days a year, I would not need a AWD car. In the Northeast, there is almost no RWD stock around, its actually cheaper to buy a AWD car off the lot than to order one from Germany. If one consider the cost of snow tires, rims, TPMS and labor, the AWD is actually a couple of thousand cheaper than the RWD |
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01-04-2013, 08:06 PM | #50 | ||
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And if I ever have to choose between AWD with all-seasons and RWD with winters, I'll always choose the latter. Because being able to stop without the help of the trunk of a car in front of you is a million times more important than being able to drive up a hill. |
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01-05-2013, 02:26 AM | #51 |
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There are a lot of RWD vs AWD threads going on in this forum right now, and it seems you are trying to argue your point in all of them. Are you an Haldex rep?
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01-05-2013, 10:26 AM | #52 |
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01-05-2013, 10:50 AM | #53 | |
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Keep in mind the BMW AWD system is fairly unsophisticated, defaults to 40% front/50% rear (read, increase understeer at all times) and has open differentials front and rear. The system does not integrate torque vector steering or even an LSD. Thus, it simply cannot improve handling - contrary to claims here. (Unless you are one of the few who actually believes front wheel drive improves handling over RWD, asserting the nonsense that FWD "pulls" the car through turns. ) XDrive is great for straightline movement/acceleration on slippery surfaces and should be purchased by those more comfortable with such a system in the winter. It is otherwise extra weight, lesser handling, increased cost. Your choice. |
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01-05-2013, 03:52 PM | #54 | |
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01-05-2013, 04:38 PM | #55 |
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That's right this is all about choice and acceptable risk. RWD is not a no brainer and AWD is not a no brainer either. Its all about your usage, climate, and acceptable risk level.
In MTL, OTT, TOR, what did we do before AWD was common? I don't ever remember getting stuck in my father's old cutlass when I was growning up. I'm not saying AWD doesn't help. Of course it does. But do "I" need it? Nope.
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01-05-2013, 04:48 PM | #56 | ||
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For a Canadian-equipped vehicle, it's 60 kg (130 lbs) heavier. Not 300 lbs. And that's very low-slung weight as well.
The comments about increased understeer are being bandished without any qualification. Increased understeer is possible in a very limited set of circumstances, but most times not. Such as if you're plowing the front end through a steep corner on full throttle, and the outside wheel has already lost traction. Here's some marketing speak for the bored: Quote:
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01-05-2013, 07:27 PM | #57 | |
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The marketing sources you cite are describing what the car does when the tires are actually slipping on the pavement from too much power. This has nothing to do with the fundamental handling balance of the car; any car will exhibit understeer or oversteer if the limits if adhesion are exceeded on that end of the car. Front wheel drive cars exhibit tremendous understeer as a fundamental handling characteristic, as well as torque steer upon throttle application. This does not mean the front wheels are spinning. AWD cars exhibit precisely the same characteristics of a FWD car to the extent the front wheels are powering the car. Also, keep in mind the front wheel slipping under power understeer being addressed by xDrive is directly caused by the xDrive system itself! This form of understeer will never occur with RWD so there is nothing to "fix.". This is yet another example of xDrive understeer. Last edited by Elk; 01-05-2013 at 08:19 PM.. |
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01-05-2013, 09:03 PM | #58 | |||
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AWD cars still have the rear wheels pushing the back of the car, which is fundamentally different from a FWD vehicle. So no, an AWD car does not understeer in proportion to the power delivered to the front wheels as your argument suggests. This is fundamentally and physically false. Quote:
That's why I stated that the xDrive system could produce results that were "quite similar", not identical. I clearly stated that under a limited number of circumstances, the AWD had a higher propensity towards understeer. However, the BMW system does a very good job of managing this phenomenon when the vehicle is pushed hard, and compensates well. And when the vehicle is not being driven past 99%, it's entirely a non-issue. So what's the end result? Maybe a tick higher lap times with the RWD, but in every-day usage, you'd be picking nits. |
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01-06-2013, 05:48 PM | #59 |
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This is only true for a spherical car in a vacuum. If it applied to real cars just like you're describing, all AWD cars would have perfect neutral handling. For some reason, however, throughout many generations, a 3 series could always turn better than an A4. Do you have a good explanation for this?
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01-06-2013, 07:24 PM | #61 | |
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Either way, the invoice price of an XI is $1800 more - so assuming you can negotiate the same deal on either vehicle, you can get winter tires, TPMS, fancy rims from Tirerack for around $1100. So I don't get how you can do the math and say that AWD is in any way shape or form a couple thousand cheaper. At very best it's several hundred more expensive and you still don't get the added benefit of snow tires. AWD helps with handling, but when you have to stop short because it's snowing your AWD means nothing, and you're left to the will of your all seasons. A RWD car with real snow tires might save you from crashing into the rear of that truck - so winter tires even on AWD are still worth the investment.
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01-06-2013, 07:33 PM | #62 | |
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I've stated that there are situations where the AWD 3 will still produce increased oversteer. If it produces increased oversteer before reverting to RWD in those circumstances, it will be marginally worse in performance in those circumstances. The system takes a bit of time to transfer the power (up to a tenth of a second after it's registered), so one would still be subject to both the increase in initial understeer plus this delay. Further, the AWD will have different handling and more notably different steering feel (heavier and prone to torque-steer). They're not the same, and you can't drive them like they're the same. So, no, I don't think AWD better, nor neutral. It's different, with some disadvantages in some circumstances, and some advantages in others. The points I made were both to correct some inaccuracies as well as calm down the exaggerated rhetoric. It's a slight difference overall, and only in circumstances where the vehicles are pushed to the limits do these differences really come to light. Comparing to a different make of vehicle is apples to oranges, so doesn't really provide a useful metric. I could compare the RWD 3-series to our decade-old Porsche Turbo or the GT-R, and the AWD platforms would steer circles around the RWD 3'er, therefore AWD must be better? Not valid. Drive the Turbo next to the GT2, and again the RWD feels sharper. |
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01-06-2013, 07:35 PM | #63 | |
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Then they're in the ditch scratching their heads... |
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01-06-2013, 09:22 PM | #64 | ||
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That is, xDrive can only address the loss of traction induced by xDrive transferring too much power to the front wheels in the first place. Ironic, at best. It is not coincidental that the best handling is achieved by not transferring power to the front wheels in the first place. Quote:
The problem with AWD and turning: any front tire traction used to propel the car forward cannot be used to turn the car. This inherently decreases the ability of the car to turn. With RWD, all of the front wheel traction is available to turn, one of the reasons RWD handles better (there is also AWD torque steer, weight differences, etc.) This relative unwillingness of an xDrive car to turn is easily felt in day to day driving. A car using only 50% of its capability to turn feels very different than a car using 85% of its ability in the exact same turn. This is why a sports car feels much more comfortable than a sedan in a corner; it is working much less hard. This is one significant difference between RWD and xDrive. xDrive is great for increased traction in snow and on ice while going in a straight line. This ability has its costs. Only the individual buyer can determine whether the compromise is worth it. This is a perfectly valid choice. |
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01-06-2013, 11:13 PM | #65 |
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I'm trying, from a physics point of view, to follow this strange discussion.
Do people who buy BMWs not have enough funds to get both xDrive AND snow tires? And I'd think xDrive and snow tires both help handling is slippery conditions, either alone or doubly together. Why the extended discussion of either/or? I bought the xDrive, and if I need snow tires, I'll get them too. And I don't get the claim that xDrive only helps while traveling in a straight line and accelerating. Whenever a wheel starts to lose grip, its traction diminishes, dynamic friction is less than static friction. Unless one is just coasting, with no breaking nor accelerating on any of the wheels, xDrive can reapportion the force on all wheels to reduce the number of wheels slipping and the differential rate of slip. Wheels can slip (or have traction) accelerating, breaking, or from centripetal force while turning. The statements "A car using only 50% of its capability to turn feels very different than a car using 85% of its ability in the exact same turn" and "a sports car feels much more comfortable than a sedan in a corner; it is working much less hard" are also mysterious to me. |
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01-07-2013, 08:37 AM | #66 | |
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