Can anyone comment on E70 vs. E53 in snow?
 

I had an 04' X5 3.0 and I used snows on the OEM rims (it was LCI with xdrive). The DSC on that model was designed to allow some sliding before it kicked in. I read in BMW literature that unlike a rear drive BMW sedan where the DSC takes action immediately when traction is lost in a corner, the Xdrive models allow the 4 wheel drive system a shot to correct the situation and restore traction, and if that fails only then does the DSC kick in with the individual wheel braking etc...

Bottom line was that the old X5 was not as goof proof in a corner in the snow as my rear drive 740/325/550 were (although they'd get stuck starting from a stop light going downhill!). The stability control was noticeably slower to act (as you head for the trees).

Well, I just got my wife an 09' E70 4.8 sport. Great car so far. I'm going to get 18 inch wheels with 255/55 snows for next season.

So, is the new E70 more confidence inspiring in the snow than an E53? Its a lot heavier than my 6 cyl. was. I'm sure there have been changes to the xdrive system and the flexray network on the E70 allows for superfast data transfer to the DSC. Does anyone have experience with both X5s in the snow?

Thanks,
DRP

No personal experience, as I haven't driven an E70 in the snow. 2004 onwards E53 uses x-drive, same as the E70. E70 weighs more, so it wouldn't do as well in the snow in theory. What it really comes down to is tires; compared to that factor everything else is essentially irrelevant. I would be interested to hear from owners who have had both, with the same tires.

I live in Minnesota and the E70 (6cyl, non-sport) was fantastic this year with the stock OEM runflats. It drove better than the 2007 Acura MDX I had before it.

I was very surprised, I did not expect the tires to work that well.

I really don't have much snow time in the E70. It performed well during the few times I drove on somewhat bad roads, but I was away for the storm we had a few weeks back. I know I am less confident in the E70 because I'm running all seasons on 19s. My '05 E53 was great in the snow but I ran snows on 18s. Not a fair comparison really. Liek JCL said, tires make the difference.

The E70 is fantastic in the snow with snow tires. Can't compare to E53 but I've never been a better vehicle in the snow...

Can't compare to the E53, but when I did some informal testing of the DSC/DTC and with it off, there was a noticeable difference. I tried to do a quick 180 and you can feel the DSC prevent the spin halfway through it. I don't know what that was in actual seconds, but it reacted enough to help me gain traction (even if I tried to prevent it). All this was done on 20", all-seasons (the whole reason for the test). Have driven in snow quite a few times with them with no traction or real slippage problems. If you live in an area that gets snow more than 10 times a year though, snow tires are safer of course.

it mostly comes down to tires.

Forgot to mention that I owned a few E53s also. For me, the E70 is better in the show. But -- YMMV since the tires made a big difference. If you have decent 18" all seasons on the E70, I really don't think that snows are needed. The only place that snows would help is for extremely icy conditions.

I know it was a challenging winter here because my wife complained about her car all winter in the snow. I never had a problem with the E70.

Ok I had a 4.4 with Scorpions(for snow) and my 4.8 has stock 19" wheels/rubber. the stopping is not even close but the get up and go is just as good. The new Xdrive rocks compared to the previous e53 systems. BUT.... I believe 100% in winter setups so i will have a winter setup next year but you will be very happy with the new xDrive

I have driven the E53 on ice and in over half a meter soft snow in Sweden, close to the polar circle, a few months back (yes the car is standing on the road, temperature around -28C). I managed to get to the place at the picture but although it was soft snow, I was not able to get any further since the road is rather steep uphill at this place. So, I got stucked and had to reverse and park the car and walk the last few kms to the house with some of the luggage... That took me a while in that weather.. :confused:

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I am now driving an X6 with same set of winter tires (Pirelli Scorpions, 19" and a bit wider). I did not try it in one meter snow yet but I can tell you that the handling on snow and ice is miles better than the E53, which also was a very competent car. So, the E70 would surely be better than the E53 since the xDrive-system has been improved and the ground clearance is an inch or so better than before.

The only difference to the E71 would be the DPC, which of course does help on snow a lot when you have different friction between left and right (for example left wheels on ice, right wheels on snow). In this case the DPC will divert the torque sideways between the backwheels. Another situation is while cornering on slippery surface where the DPC will kick in and shift the torque to maximize the cornering speed and suppress understeering.

The day E70 gets the DPC, I will place an order. Do not understand why they do not provide the X5 with this nice feature, especially as the X5-owners are more likely to use their cars on such places than the X6-owners.

Thank you for that great repsonse
 

That was exactly what I was wondering about. I convinced a friend to get an X6 5.0 which he just ordered. He says his current range rover is excellent in snow and asked about the X6 (he will be using snows on the BMW, but didn't on the Rover). I think he is going to be very pleased as long as he can learn to be gentle with the gas pedal.

I got a lot of responses on this post from people who liked their E53s in the snow. That was not really my question. You answered my question as to whether the E70 is better. I realized afterward what my definition of a car that is "good in snow". It is this: The closer you can get on snowy roads to the average speed you travel in dry conditions, the better your car is in the snow. It's not about getting stuck. Its a combination of acceleration, braking and handling on the snow and ice that all combines to give you confidence (or a lack of it).

Thanks again. Enjoy the E71. It was going to be my next BMW until I got my wife the E70.

DRP

Thanks DRP. You will surely be positively surprised of the capability of the E70 in snow and on ice. The DSC-regulation is faster and less aggressive, which means that you could drive closer to yours and the cars limits with reference to available grip before the system kicks in and when it kicks in it will distribute the torque in a faster and more subtle way than the E53 does wich will make you not only drive faster but also with a better body control.

Everyone telling that BMW does not build capable cars for difficult conditions does not know what they are talking about. I have driven many different cars in severe snow storms and temperatures around -40C. No one of the other brands have been as good and as reliable as the E53 and now the E71. The traction from the xDrive is just superb (with snow tires), the heat from both petrol and diesel are great and the cold start capability is better than any other car I know.

In some winter tests in Swedish and German car magazines the traction from the xDrive models have been found better than the equivalent systems from Audi, Volvo, Mercedes, Subaru, Land Rover etc and equivalent with the mighty Landcruiser (BUT with the possibility to go fast also in the bends...) :-)

So, congratulation to you and your wife owning one of the best winter cars available! Enjoy the next snowfall!

You are comparing the X6 (E71) with DPC to the E53, and drawing conclusions based on the X6 performance. Yes, the difference was noted in a post above, but it is the defining difference in the two models (apart from the E71 engines). The original poster's question was about the X5 (E70). The problem is that as far as I know, the DPC system on the X6 is not available on the X5. BMW is using that traction control system to differentiate the two models. So, it is comparing apples and oranges. The E70 has essentially the same x-Drive system as the post-2004 E53s. We can talk about response times in the DSC system, but at the end of the day, I think it really comes down to tires and weight. Tires can be made to be equal, but the E70 is still heavier, and weight is the enemy.

There is also a comment that the additional ground clearance of the E70 will make it better handling than the E53 in poor conditoins. I disagree. It has a higher centre of gravity, and that will give it worse handling, all other things being equal. The additional ground clearance only matters in deep snow, and it is only marginally different. Snow conditions will matter more than the small difference in ground clearance in my experience.

Kungen, I agree with you on the all-weather capability of the X5. No question in my mind, it is a very capable vehicle with the right tires. Most of the discussion on the limited capabilities of the X5 on this forum and others is about off-road driving, where ground clearance and other issues come into play.

I took my Volvo XC90 to Nordkapp and had no problems with pirelli scorpions. Now with E70 I would not dare to take this trip with the same tires. My father has a Landruiser and I can tell you that it is the best on the snow among the three.
Just my opinion.

Well, the FlexRay response time of 2.5 ms is surely contributing to make the feedback of all systems (damping, DSC etc) a lot better. As you know, the enemy of grip on slippery surfaces is not the weight (purely physically) but slow adjustments of the different systems. This is why Volvo with the Haldex III version has no chance against for example the BMW xDrive system. The Haldex system shifts 90% of the torque to the front wheels and is able to theoretically shift over 50% of the torque to the back wheels in 1/8 rotation of the wheels. This 1/8 rotation is a disaster when it comes to grip on slippery surfaces. You can just read all the test of 4wd systems and you will see that they all come to the same result.

I was testing the grip i Sweden this year between a 2004 E53 and a XC90 in different gradients and different friction coefficients between left/right. There were identical set of tires between the cars and the difference was huge. When the XC90 was standing still, spinning, the E53 was gently finding grip in almost any situation thanks to the fast regulating xDrive.

In for example "OffRoad" 2/09, different systems were compared and the X6 had the highest speeds in slalom and exacly identical time in acceleration on ice uphills like the Landcruiser. The Volvo XC 60 (with Haldex IV) and Jeep Cherokee had no chance in any of these disciplines.

Regarding differences between E70 and E53, does not the E70 have a standard setup with 60% torque to back and 40% to front, while the E53 have 50/50? At least this is what I can recall, Audi has followed and changed their successful Torsen 50/50 to 60/40 as well, which gives a lot better drivability on curvy roads (less understeering).

Only my opinion...

Regarding the increased ground clearance, the improvement was of course intended for deep snow conditions. On slippery roads the increased center of gravity is not making almost any difference for the handling since the resulting force between the vertical force from the car's weight (from center of gravity) and the horizontal force from the resulting friction of the tires will end well within the contact point of the tires and thus not create almost any roll or shift of force between the tires.

On dry roads, where the horizontal force is high it is of course important to have as low center of gravity as possible. It is however the quotient between the distance between the wheels and the center of gravity that is of essence (i.e. the resulting force), not the center of gravity alone.

I would guess that the E70 has a better ratio than the E53 here (wider track and probably not too much increase of the center of gravity), which theoretically would allow higher curve speeds on dry.

Kungen:

You gotta love debating with engineers! Not slamming you, as I am one, as I suspect you are. :thumbup:

While Flexray may be faster, I don't think that the x-Drive E53 had problems with response time. The pre-2004 models did have limitations there. Neither is directly comparable to the Haldex system which is an add-on to a FWD car.

The E53 has a 62/38 torque split. I thought that applied to the pre-2004 models, as well as the x-Drive models, but I could be wrong.

Your comments on centre of gravity are primarily considering static forces, or at least steady state forces, not dynamic forces. Given a choice, a lower centre of gravity is much more preferable, for the benefits in roll centre, transient responses, etc. I struggle to understand how any vehicle with the same AWD system (E70 vs E53) is going to handle as well when it weighs more, and has a higher CoG. You can compensate for it with DSC, but you can't overcome physics. Just my opinion.

Wider track will help in cornering (theoretically) but it doesn't help in braking. Weight and CoG will be the enemy there. Importantly, a driver at the limit is never doing one thing, whether it be braking, cornering, recovering, or whatever. They are usually doing several of those at once. That is why it becomes an issue for dynamics vs static considerations.

We could debate the finer points of the above, but my comments really were that all things being equal, it doesn't matter because tires play much more of a role here than anything else, and the X6 is a different animal because of the DPC.

I have driven in -30C, but not in that much snow (at least in our BMWs). I have pushed snow deeper than the bumper with the E53, and with a 325x. Both had the same (Michelin) tires. The 325xi walked circles around the E53. It simply weighed less. it had far less ground clearance, but that didn't matter compared to the weight issue. Everything else was essentially equal (OK, manual vs automatic).

If we look across the wide range of posts on this board, there are those who are running their tires at 40+ psi to improve handling, and others who are happy with the winter/snow performance of their 20" all season tires. What I am suggesting is that you and I are debating the final 1% or 2% delta, and may be on our own here. Still an interesting debate, though. :thumbup:

Pre X-Drive E53s indeed had a 38% front/ 62% rear torque split. With the introduction of X-Drive the torque distribution went to 50/50. This, of course, only applies on a high-traction surface under normal operating conditions.

I went and looked it up (since my memory may be fading). BMW websites I checked state that it is 40/60 F/R nominal torque split, but variable depending on traction. This preserves the RWD feel.

Do you have a source that states differently?

I have a BMW tech sheet on the X-Drive E53. However it does say that the 50/50 drive is with the centre multi-plate clutch (which acts as a diff) fully closed. I presume this means locked up. So 40/60 drive is probably right when the centre diff is open. I know that BMW did make a big song and dance about retaining the feel of a rear-driver as much as possible.

This is great!
 

Witness: the power of the internet. engineers debating across continents effortlessly in their spare time.

I very much enjoyed reading the posts. But I still must hark back to the original question: What is the harm of using a DSC system with a low threshold of intervention on an SAV if - if - it can be changed for the dry conditions via a switch? The M cars have an alternate traction mode "M dynamic" which allows for more wheel spin and sliding. Why can't the X cars have the ultra sensitive DSC from a 3/5/6/7 series rear drive car? Call it "winter dynamic mode" right?

I don't understand the need to allow the 4 wheel drive system the opportunity to regain traction? I'm sure there's more to it than I am aware of. You don't want the traction light going off because you hit a bump in the corner while accelerating. I understand that traction/stability control can be too sensitive in dry conditions (a complaint of many AMG mercedes drivers), but what's the harm in offering a winter mode?

Example: your heading down a secondary road at 70 km/h on packed snow in your E70 and you need to make an abrupt turn onto the next side street. You brake and then turn, but you're going just a bit too fast and the front end (only) looses traction and the arc of your turn increases enough to put your vehicle onto the other side of the road facing oncoming cars. At no point in my example has the accelerator been used. Therefore, the X-drive is not being used either. If you were in a 530i doing this, the DSC activates and brakes the inside rear wheel and brings your car back into the correct lane. With an E53 X5 you slide into the next lane unless you exaggerate your turn by cranking the steering wheel into the turn which "wakes up" the intentionally dormant DSC. Then the car somewhat overcorrects due to your exaggerated steering input. I'm guessing that the DPC on the X6 does much of the the job done by the aggressive DSC on rear drive BMWs info far as correcting slide in a corners in concerned?

Can anyone defend BMWs decision to calibrate the DSC this way on X cars?

Thanks again for the great input.

DRP

Have you checked out this thread:

http://www.xoutpost.com/x5-e70-forum/...itzerland.html

I think it comes down to the fact that fwd/rwd/awd vehicles have different cornering dynamics, especially with limited traction. Your example assumes that the cars are all driven the same, and that is not what should happen. It is an example of driver error. The awd benefit is only there if your foot is in it. In your example, the driver went too fast for the conditions, and then drove through the corner without throttle. Two errors that compound. If he went slower into the corner in your example, and then accelerated to let the awd system do what it is designed to do, this wouldn't be an issue.

I think that if you want the awd system to work as designed, you need to allow the nanny devices enough tolerance to let the drive systems work, ie not correct for a situation if in fact it is just a case of the drive system doing what it is supposed to do.

There was a thread awhile ago where a member posted that his new X5 didn't seem surefooted on snow, and he wasn't confident in the cornering of the vehicle. I suggested that he keep his foot in it (within reason) and let the system work. His response confirmed that the approach worked. I think the DSC is just doing the same thing, letting the awd work. Since BMW isn't about to add throttle automatically in those situations, that action will remain a driver responsibility, and rightly so.

That isn't intended so much as a defence, as much as a comment on why the different programming may exist.

Hmmm, I had actually decided to enjoy the Friday evening with doing just nothing but you are right, what is better than debating technical details across the globe with clever people? :iagree:

Feel the need to throw in some sticks to the fire. Actually my reasoning with the center of gravity is based on dynamic calculations (Lagrangian mechanics to be specific, which together with chassie dynamics was my field of study - well concluded JCL :thumbup:) and not statics.

To clarify my reasoning, a low center of gravity is always preferable for the handling, holding all other parameters constant. Between E53 and E70 there are however some major differences/improvments made which IS changing the parameters:

- The body is stiffer
- The track is substantially wider (68mm front, 74mm back)
- The dampers are faster (Flexray)
- The wheelbase is larger (113mm)
- The DCS is improved (ver. E7x)

To this should be added that according to the spec the weight is only around 15kgs higher for equivalent model at E70, while the center of gravity (CoG) has increased from 678mm to 680mm (i.e. with 2mm).

There are other improvements made which would play a role on dry like the active anti-roll bar. The active anti-roll bar does limit understeer behavior and is tuned by changing the proportion of the total roll stiffness that comes from the front and rear axles. Increasing the proportion of roll stiffness at the front will increase the proportion of the total weight transfer that the front axle reacts and decrease the proportion that the rear axle reacts. This will cause the outer front wheel to run at a higher slip angle, and the outer rear wheel to run at a lower slip angle, which is an understeer effect.

All in all, the physical improvements between E70 and E53 are a lot more substantial than the deterioration of the weight and CoG (unsubstantial). It should be noted that it is the relation between the track and the CoG that is important, not the CoG itself. Weight is an insignificant factor for handling if the corresponding parts are upgraded (tires, brakes etc). As an example, a light bicycle with four wheels is not able to perform higher cornering speeds than a big SUV due to insufficient friction from the tires. :wtf:

The above reasoning is valid mainly for dry conditions but the question was actually performance in snow. In slippery conditions the CoG has significantly less importance since the curve speeds are lower due to lack of friction (type of tires are VERY important). Consequently, the horizontal force and corresponding roll is less than on dry.

In the DTC mode (one push on the button), the system allows more spin/skid before the "safety belt" (DSC) is activated. This is perfect if you want to perform highest possible curve speed without risking doing a 360 on the road...!ouch:! :loco:

the DPC in X6 is working both on- and off throttle. DPC uses an electromechanical system of two planetary gearsets, a multiplate clutch, and an electric helper motor to divide torque between the rear wheels. The DPC thus supress DSC to a maximum with improved drivability in the curves (and traction on the winter road). So, as a matter of fact BMW DOES add throttle automatically in the situation Pex5 is describing. :bounce:

Here are some interesting documents I found on the X5word's homepage(OK, a bit simplified descriptions):

Kungen:

You note that the CoG is only 2 mm higher. I didn't have the specs, but the E70 is 50 mm taller, so I would have assumed it was more than a 2 mm difference in the CoG.

You note 15 kg more for the E70, and that same number is in the BMW training material you link, but published figures for both vehicles show a 350 lb/160 kg difference. That is probably due to the standard equipment in the North American market, as compared to the bare vehicle. The weight increase is also consistent with the performance reduction of the 3.0, even though it went from 225 hp to 260 hp or thereabouts.

I don't disagree with your comments on dry road handling, but with respect to the snow handling performance of each vehicle, I think it still is pretty much 98% about the tires.

The DPC system (in the X6, not the X5) does vary the torque split between wheels, but I didn't know that it added throttle. I would have said that it rebalanced the throttle. I wasn't referring to simply backing off the power to one axle by varying the torque split, but to actually powering through a corner.

Good discussion. :thumbup:

Our X5 E70 is a beast in the snow with the stock set-up it was delivered on. By far the best riding/handling vehicle I have ever driven in bad weather. I look for snow/ice to "play" in when given the chance.