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BMW 3-Series - AWD or RWD?

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  • nicely said, but just would like to add to the end of your statment. not the same as the 335i but its still there & beyond with certain road elements.
  • getzgetz Posts: 24
    I think AWD is a natural evolution of automobile technology, and just like advances in any field, there is always resistance. Preferences regarding driving dynamics, feel, as well as a history steeped in tradition all combine to make convincing arguments about staying with a recipe that "aint broke". I remember posting on a edmunds 3-er forum a number of years back, stating that I would love to see a turbo-charged bmw inline 6. That post was met with so much acidity that it was laughible, and I recall one member stating that the day he saw a forced induction fed bmw, would be the day he stopped buying the brand. Well, I must say, the new twin turbo inline 6 is nothing but joy, and a beautiful example of technological progression. All the arguments against forced induction have been met, and overcome, providing a beautiful combination of terrific low end grunt, a nice top end, and seamless acceleration with no hit of turbo lag. I wonder if the gentleman that was so adamant that a turbo bmw would be a horrific injsutice to bmws' tradition of naturally aspirated engines would still feel the same today?
    Regarding AWD, vehicles are getting closer and closer to delivering handling dynamics similar to their RWD counterparts, and it's only a matter of time before we reach the point where the benefits far outweigh the downside of handling feel. Just like the progressions of clutchless manuals....which you can still operate identically to a traditional manual, yet still keep two hands on the wheel, there is a very positive benefit to the technology, not only regarding performance, but safety as well.
    I still think the ultimate performance combination lies in the hybrid concept. Having almost unlimited torque off throttle using an electric motor, with a rev happy gasoline engine waiting to flex its top end muscle seems like a wicked combination, however, it will take years to perfect. And will also be met with a zealot like hatred from traditionalists. Similar arguments can be met for placing rail injection diesels in sports cars....which has also met a large amount of resistance from diehards. I'm of the mindset that if it makes it safer, faster, easier to drive, then its probably a good thing.
    -Getz

    P.S.
    I'm open to an 8 wheel, individual motor per wheel, Frank Herbert type hybrid if it is better than the current set up, just as long as it has an ipod adapter.
  • fedlawmanfedlawman Posts: 3,118
    One point about X-Drive that hasn't come up yet (and I'm surprised it hasn't, because it's well known on the SUV side of the house) is the fact that X-Drive is strictly a front-to-back torque transferring system.

    Imagine you are negotiating a big, left hand sweeper and approaching the friction limits of the (right side) tires. As you continue into the corner, the right front wheel has a higher slip angle than the right rear, and will break traction first (understeer). In the blink of an eye, X-Drive transfers torque away from the front axle and sends it to the rear axle. Now as you continue through the corner with more rear-biased torque (neutral), both right side tires (front and rear) start to slide at the same rate. What does X-Drive do here? Nothing - it's incapable of transferring torque away from the slipping right side and over to the gripping left side. Instead, DSC will apply the brakes and/or reduce the throttle until the car slows enough to stop sliding. And since there is more curb weight, more front axle biased mass, and a higher/softer suspension, lateral weight transfer is more exaggerated. This translates into lower overall lateral grip, and earlier DSC intervention.

    Same phenomenon in quick transitions such as the slalom or a tight S turn. Turn one way and you place a greater load over the 'outside' side of the car, while unloading the 'inside' side of the car. Then when you are abeam the cone and turn the other way, you have greater weight transfer to the other side of the car (due to more suspension travel and greater mass), thus resulting in a larger magnification of lateral forces acting on the new 'outside' side of the car, and a greater lifting of the 'inside' side. As you progress through the slalom, the side-to-side transfer of weight shift magnifies with each repetition - an effect that X-Drive cannot compensate for. What's the solution? You slow down.

    Bottom line? All else being equal, the 335xi can not generate as much lateral grip as the 335i. Period.

    Caveat: Since of course it will come up - The fact is, for most (read: unskilled) drivers, the 335xi will probably be just as fast, or faster than the 335i in these situations simply because the driver is incapable of identifying the onset of understeer and feathering the throttle to shift weight rearward. It's all theoretical exactly when understeer and torque transfer will happen in a corner, but it's undeniable that the 335xi will 'feel' more neutral to the untrained driver because they may never detect the onset of understeer.
  • thank god i didnt sell the z06!
  • circlewcirclew Posts: 8,355
    OK, now what if you "turn off" DSC/TC? I assume the slip angle at the limit in the turns allows the car to slide out to the side of the car with the load since the driver identifies the he is loosing grip at the limit and can then feather the throttle and instead control both front and back axles through each turn at greater speed. If overdone the car slides off the road side ways instead of rotating from sever over steer and "spinning" off the road.

    Done correctly, the car slides through each turn under more control and speed than the RWD... and pulls out of the turns a bit quicker with all 4 wheels providing power on.

    Just my interpretation.

    Regards,
    OW
  • roadburnerroadburner Posts: 6,304
    I would feel privileged if you would tell me how rich the leather smelled, you lucky son of a...

    Actually, I was surprised that the leather didn't have the cool Alpina stitching- although the steering wheel did- go figure. Anyway, here are a few pictures from my CarSpace album...

    The B7 and a real M3(Also note my exclusive painter's tape car number):
    image

    Another angle:
    image

    With a TC Kline Carbon Coupe:
    image

    At the Concours:
    image

    What 500 bhp of supercharged V8 looks like:
    image

    How to keep a final drive REALLY cool:
    image

    2009 328i / 2004 X3 2.5/ 1995 318ti Club Sport/ 1975 2002A/ 2007 Mazdaspeed 3/ 1999 Wrangler/ 1996 Speed Triple Challenge Cup Replica

  • shiposhipo Posts: 9,152
    Uh-oh, I see DTM plates. In New Jersey that's a dead give away that the car is owned by the manufacturer. Having worked for a few years in the mid 1990s for MB-USA, I couldn't turn around without seen several DTMs. Then after I left MB, my wife and I built a house on Glen Road in Woodcliff Lake, and if you are familiar with the area you'll know that BMW-USA is located at the corner of Chestnut Ridge Road and Glen Road, right down the street from our house. Yup, you guessed it, more DTM plates. Yeesh! ;)

    Best Regards,
    Shipo
  • roadburnerroadburner Posts: 6,304
    I compared the plates and discovered that this was the same B7 that Car and Driver tested. I seriously doubt that I beat on it as hard as they did- although I did discover that the Service Information System thinks that three 30 minute track sessions are equivalent to 900 miles of normal driving- at least with regards to oil life...:P

    2009 328i / 2004 X3 2.5/ 1995 318ti Club Sport/ 1975 2002A/ 2007 Mazdaspeed 3/ 1999 Wrangler/ 1996 Speed Triple Challenge Cup Replica

  • fedlawmanfedlawman Posts: 3,118
    This was the year I should have gone to O'Fest, and I didn't. Looks like you had a great time! I assume you're writing a story about O-Fest?

    That's a very nice looking Warsteiner E30 M3 replica (I assume it's a replica). It doesn't look like MJ Calabrese's car, do you know anything about it?

    I remember seeing the same TC Kline Carbon Coupe at TechFest. My car was on display in the hotel - parked 5 cars away.

    image
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  • That car is stunning, and will out perform almost anything compared to it. I also drove the C4S/C2S extensively, and felt as if the C4 was faster from a stand still.... Although my track car is a RWD setup, its hard for me to bash awd cars,.... and have much more neutral driving characteristics of old. If I am lapping the Nordschleife, put me in an AWD supercar any day of the week,

    As an owner of a 2007 911TT, I sincerely appreciate your compliments and enthusiasm for the car. For the majority of prospective buyers out there, it is indeed the "ultimate" 911. I have absolutely no purchase regrets. However, in looking for the best of all worlds - power, nimbleness and handling, I have placed myself second in line (behind the owner of the dealership) to get a GT2, which is essentially everything the 911 TT is, without the weight and bulk of AWD.

    In the case of the GT2 vs. 911TT, my preference for RWD over AWD is almost strictly handling based. The lighter weight and different mechanical setups makes RWD my strong preference, all other things being equal.

    However, in the C2S vs. C4S, both of which I seriously considered and extensively test drove before getting the TT, I don't understand how you could have concluded that the "4" was quicker off the line than the "2". There is nearly a 5% additional drivetrain loss of power in the 4, as has been documented in dyno tests. And the added weight of AWD extracts a noticably bigger penalty with "only" 295 ft-lbs of torque, compared to the TT's 500. I am quite certain that a 325 hp base C2 will give a 355hp C4S serious competition "off the line". The C2S is, in reality, considerably quicker, in addition to being nimbler. These facts are not reflected in Porsche's published performance data. Both the C2S and C4S are listed at 4.6 seconds 0-60. However, in Porsche's convenient way of conservative marketing, the C2S has been road tested as quick as 3.9 seconds and is damn near as quick as my friend's 996TT. The C4S, while still very competent, is simply not in that league, "off the line". The advantage of the "4", at least in the vastly improved 997 model, is strictly in poor traction (rain, snow, gravel) conditions.

    As far as Nordschleife or Nurburgring, does it surprise you that the RWD 997 GT2 has surpassed the $450k V10 AWD Carrera GT in lap times? Or that the 415 hp RWD GT3 easily surpassed the 480hp AWD Turbo? Had it not been for the introduction of the GT2, I was seriously considering getting a GT3 after having the opportunity to drive that beauty. The handling is exquisite and I hate to admit how bulky my TT felt by comparison after an hour in a GT3. With the PASM set on normal mode, it didn't even rattle my fillings loose, like the 996 GT3 did a few years ago.

    Again, I appreciate your compliments and enthusiasm for the 911TT, and it is an exceptional car. But, frankly, it deserves much of the accolades heaped on it in spite of being a heavier AWD setup, rather than because of it.

    The "truly dedicated" award in the 911 line goes to the RWD GT3 and the ultimate performance goes to the RWD GT2.

    From your lips to my wallet.

    P.S. I apologize for the lengthy digression into the world of the 911, when the forum is supposed to be about the 335i vs. 335ix. I have only ever driven my nephew's 335i (sport package). I cannot comment upon the 335ix, other than to say, the laws of physics still apply. Weight is weight, and drive train efficiency is always reduced when you add more moving parts and connections to the system. Suspension and wheel/tire differences also need to be considered. That said, if someone prefers the road surface versitility of AWD over the performance and handling of RWD in a sport sedan, so be it. Either way, these are two very impressive cars.
  • getzgetz Posts: 24
    I agree generally with all your points, however, I embrace the fact that I will never, ever, be in the same league as the likes of Walther Röhrl. So with my average ability, I will almost always lap an comparably powered awd vehicle faster than a rwd vehicle. I tested both the c4/c2 on backroads of occasionally less then ideal surfacing, and to my butt dyno the traction of the awd overcame the 200 lbs of extra weight. As I live in the northwest, the saved winter headaches of having awd more then makes up for the addition of 200 lbs. Regarding the GT3, it is undoubtedtly sweet, and available in lime green to boot, enjoy.
    -Getz
  • circlewcirclew Posts: 8,355
    Popularity of AWD cars revs up

    Royal Ford, Globe Staff
    September 12, 2007

    One is an American luxury sedan long associated with rear-wheel-drive muscle, the second is a zippy descendant of the German "people's car," and the third has a minivan's utility with performance that surpasses some sports cars. But the Lincoln MKZ, the Volkswagen Passat, and the Mazda CX-7 have something crucial in common: They are all available with all-wheel-drive.
    AWD passenger cars are becoming increasingly popular with drivers who want improved safety without the added weight and - usually unnecessary - off-road capabilities of a SUV. With AWD, four wheels are in full play, as opposed to just a pair. That means critical electronic safety systems, which transmit power and braking to individual wheels, have more ways to correct for driver error or sudden changes in road conditions.
    Automobile industry studies have shown that cars with electronic safety systems - such as antilock brakes, electronic stability control, traction control, and antirollover protection, - are more than 40 percent less likely to be involved in an accident. And if a crash does occur, the systems cut the death rate by more than 40 percent. Although studies incorporating AWD have not been done yet, it is likely that the systems will further reduce fatalities.
    In 1985, Audi and Subaru were the only mainstream manufacturers selling all-wheel-drive passenger car models, according to the Environmental Protection Agency. Ten years later, the number of all-wheel-drive models reached 50. This year, there will be 86, according to the automotive website Edmunds.com, and the market is expected to continue to expand.
    George Kang, a senior analyst for Edmunds.com, said consumers have come to see all-wheel-drive as a safety feature that offers "all weather, not necessarily all-terrain performance."
    An AWD system adds about $1,500-$2,000 to the price of a car. It is standard on Subarus and most Audis. But as more companies develop or adopt AWD systems, the cost will drop, Kang said, and AWD will increasingly be made available in midrange and economy models. As a result, many car buyers who drove SUVs because of the security they offer in bad weather, will have more lighter choices at lower prices.
    Travis Hanson, an instructor at New Hampshire's Team O'Neill Rally School, said Subaru has set a standard in low-cost AWD because all of its cars share "almost the exact same drive line," whether they are basic or deluxe models.
    Although it doesn't sell low-cost cars, Mercedes-Benz has been a recent leader in promoting the widespread use of AWD. Six years ago, the German automaker said it would make AWD available in virtually all of its models.
    In the Northeast and other parts of the country where snow and ice can make driving an endurance test, AWD's popularity is soaring among Mercedes owners. Today, about three-quarters of Mercedes sold in the Northeast come with AWD. The company's C280 passenger car leads the pack, with 96 percent of its current models selling here as AWD.
    "We are in the fortunate position to be courting this niche for a long time," said Bernhard Glaser, the Mercedes-Benz general manager of product development. "But we are not surprised to see the competition trying to catch up."
    Multiple AWD offerings are also on the market from Infiniti, Lexus, Ford, General Motors, Saab, Chrysler, BMW, Subaru, Audi, Volvo, and Volkswagen. Acura, Mazda, and Porsche each offer a single AWD model.
    While older four-wheel-drive systems used all wheels continuously - and thus more gas - today's AWD systems send power to all four wheels only as needed, making them more fuel efficient. Kang said AWD typically reduces fuel economy by "about a mile per gallon," a cost he called "very acceptable in the consumers' eyes." Some models, however, can reduce fuel efficiency by up to 4 miles per gallon.
    Part of the reason for better gas mileage is the newer systems' reduced weight. For example, the Mercedes-Benz flagship S-Class has incorporated its AWD system into the transmission, meaning it adds only 75 pounds to the vehicle's weight as opposed to 200 for its predecessor. The Lexus IS 250 AWD and Infiniti G35X each weigh only about 200 pounds more than the same models without AWD.
    In Boston Globe testing in recent years, AWD passenger cars - at costs ranging from less than $30,000 to more than $125,000 - have been pushed sideways on ice and wet gravel without breaking free, hurtled across sand at more than 175 miles per hour, and pushed through a foot of unplowed snow on hilly terrain.
    "We developed it with the thinking we would put it into other brands and tune it," said Peter Johansson, a Saab specialist in front- and all-wheel-drive technology.
    He said the company didn't want to limit AWD to only its most expensive models. For instance, Johansson said, General Motors Corp., Saab's parent company, could easily use the Saab system in GM cars.
    And it may soon have to for competitive reasons. Kang said consumers are beginning to expect AWD to be available as an option when they go car shopping.
    The relatively modest cost of increased safety and performance is "a lot of bang for the buck," he said.

    Most people do not want a set of snow tires and wheels! I would rate the 335xi as the best choice in the market at this time in the ELLPS category. Period.


    Regards,
    OW
  • xeyexeye Posts: 162
    Responding to post 153:

    Actually, that's not true. Here's an excerpt from an April 2006 article about extreme weather testing of the x-drive. I've provided the link for further reading.

    "Another notable feature of the system is its ability to shift power from side-to-side. This was demonstrated by situating a vehicle so that wheels on one side were on glare ice, and wheels on the other side were on dry asphalt (the manoeuvre was made more difficult by starting on a steep incline). The power distribution at each axle is then forced to the side of the vehicle with traction (dry side) via brake intervention at the slipping wheels, as directed by the xDrive/DSC system. The result was that the vehicle was able to move forward with power only available to one side."

    http://www.canadiandriver.com/articles/pw/xdrive.htm

    I do find it interesting that the fastest production car to date (off the line and top speed), the Bugatti Veyron, is AWD. So are some of the best handling Porsches and Lamborghini's. Now why on earth would the world's most advanced car makers develop such amazing cars if they were secondary in every respect, according to some recent posts, to cars they had already produced so successfully for so many years?

    Don't even try to tell me it's because the buying public wanted a 200 mph sports car that could go get groceries in the dead of winter.

    I wonder…what could they possibly have been thinking? Curious how Audi ran away with Pike's Peak championships to the point where other racers complained that Audi had an "unfair advantage"!

    Kudos to you, OW. I read that Globe article, too. There's no denying that AWD is an unquestionable benefit in all conditions. RWD may be destined to go the way of leaded gas.
  • circlewcirclew Posts: 8,355
    xi, thanks for the kind words!

    I was going to bring up the Bugati V but I did not want to bring that AWD point into the fray since the SSC Ultimate Aero is RWD.

    At the end of the day, you drive what works for you. The xi works for me. Period, the end. On the track days I agree the challenge/fun is with RWD. I would have a hard time deciding on which 911 to buy but no problem with an ELLPS choice!.

    I need no such challenges in commuter traffic or when the weather turns nasty!

    Regards,
    OW
  • fedlawmanfedlawman Posts: 3,118
    Actually Xeye, it is true. Read the excerpt again...

    "The power distribution at each axle is then forced to the side of the vehicle with traction via brake intervention at the slipping wheels"

    X-Drive transfers power front-to-back only.
  • circlewcirclew Posts: 8,355
    X-Drive transfers power front-to-back only.

    For now...but not for long...

    Already, the system is integrated into the optional active steering technology available on its vehicles, and in the future, the company's goal of full-scale integration will be realized in its Integrated Chassis Management (ICM) technology, designed to control the longitudinal, latitudinal and vertical dynamics of a vehicle at the same time. The experience at Arjeplog suggests that this goal is close to realization.

    I just love technology and I have great respect to the advanced drivers of the world, such as yourself that have taken the time and enjoyed the experience...there just aren't that many of you that I meet on the road. As the advancements get into our future cars, I hope the fun is not lost!

    Regards,
    OW
  • xeyexeye Posts: 162
    Ok, now you're nitpicking.

    What's the difference how it's accomplished as long as the end result is an intelligent use of engineering and it keeps the general public's a** on the road?

    Obviously, you don't need any help, although I would argue that point.
  • circlewcirclew Posts: 8,355
    Yes, exactly..if the technology helps people, why not promote it?

    We can't all drive like the Andretti family!

    You need to devote your life to that. Every nuance of a car is know as soon as you get it, start it up and drive for 5 minutes. One needs to work hard for that knowing.

    Most people drive as an extension of their living rooms!!! AWD will help to some extent, so it's a good improvement is all I am saying. Add some performance that the 335xi brings and I am one happy camper.

    Regards,
    OW
  • habitat1habitat1 Posts: 4,282
    I guess I must have ADD, because without any paragraphs, that post is just too painful for me tor read in its entirety. So let me skip to the end....

    Most people do not want a set of snow tires and wheels! I would rate the 335xi as the best choice in the market at this time in the ELLPS category.

    If anyone with a 335xi thinks that their traction is better with AWD and summer tires than RWD and all season or winter tires, heaven help them. Forget the 335ix; one of my neighbors was completely stranded with an X5 4.6i with the low profile 20" wheels and tires a couple of winters ago. He had to park the vehicle a block away because it wouldn't make it up a modest hill on the street in front of his house on packed snow and ice. Short of a Cayenne S, it is the best handling SUV I've ever been in, but he immediately replaced his sport package high performance tires with all seasons the following spring.

    In the winter driving formula, tires are more important than drive wheels in my opinion and for unpacked snow, you need ground clearance as well.
  • fedlawmanfedlawman Posts: 3,118
    I'm nitpicking?!?! You're the one who brought it up.

    And actually, there is a big difference, because there are systems on other cars RIGHT NOW that can transfer 100% torque front-to-back and side-to-side. With X-Drive, the most torque you can ever get at any single wheels is 50% (100% split between left and right sides).

    On the other hand, Acura has SH-AWD. This is from Acura's website:

    "The RL Super Handling All-Wheel Drive system, introduces a whole new way to corner. Unlike other all-wheel drive systems, SH-AWD was designed primarily to enhance dry-weather handling, in addition to wet weather stability. Like conventional AWD systems, power distribution can be continuously varied between the front and rear wheels. However, with SH-AWD, the RL can send up to 100% of the available rear wheel torque to the wheel with the most traction. This effect dramatically enhances steering performance and turning precision."
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