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      08-17-2018, 08:40 AM   #67
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Originally Posted by teaston View Post
I'm sure they are great in the dry, but a road car has to work in all conditions, which rwd just doesn't.
What I think you are saying, xDrive can take more abuse from the driver in many circumstances, like being more accommodating for erratic load transfer. If that makes it a better chassis, I won't disagree, it is a good thing.

I'll put a flame suit on for this comment... can to a degree make up for less driver precision and to be frank, driver ability. Problem is, some drivers are assuming xDrive (AWD, 4WD) makes them invincible in more difficult conditions and/or push the limits, often more than is safe to do when tyre grip is the limiting factor.
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      08-17-2018, 08:44 AM   #68
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Originally Posted by teaston View Post
I'm sure it's fine in the dry but in the wet my 330d Sdrive was terrible! It hugely limited my ability to pull out of junctions or overtake cars from low-speed in the wet, not to mention ruining traffic light Grand Prix ability! It's no wonder BMW made the F30 335d Xdrive only.
What tyres?

Yep, xDrive tied to the x35d is a great combo to harness all that low down torque. I can honestly say, my TC light has never even flickered and never had a loss of traction in my current mapped 35d. It requires less skill and concentration to plant the throttle and keep traction and that in itself is a good thing. However, I've decided I want a bit more involvement and predictability in my driving now. Retro-grade to RWD? Probably. Most certainly a period of re-educating my right foot and reading the road a bit closer now.
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      08-17-2018, 09:01 AM   #69
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If the next gen 3/4 series 40i cars have an xdrive option, that’s when I’ll move to the petrol.

I won’t buy a bmw without xdrive now I have lived with it for years. I don’t require the ability to drift round corners.
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      08-17-2018, 09:02 AM   #70
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Originally Posted by teaston View Post
Xdrive is all wheel drive.

All wheel drive is technically superior to 2 wheel drive in every single way, The only drawbacks are extra cost of manufacturing and slightly lower efficiency on the smaller underpowered engines. Why you'd make such a nonsense statement is beyond me.
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      08-17-2018, 09:18 AM   #71
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Originally Posted by teaston View Post
And you sound like the septics whining about manual transmissions being phased out!

I can understand the attraction of rear wheel drive back in the old days when cars had less power, but now the big engine cars have far too much power and torque to reliably put down through just to wheels. Things move on and things have to change, but there will always be those who want to resist change.
Are you familiar with the phrase "when in a hole stop digging"?!
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      08-17-2018, 09:19 AM   #72
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X Drive thread. Guaranteed 10 pager on UK section

I think realistically AWD vehicles will be the norm on all but entry level brands. I'll be pretty surprised if the new M3/4 isn't the same as the F90 now with how well it's been received.

Performance S Drive type cars will be becoming collectors items pretty soon.
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      08-17-2018, 09:32 AM   #73
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Different conditions... I'll come back to this as I'm just going out.

There is a big difference in slow speed control, than decelerating from high speed.

We've used the descent control (hill assist) in my son's X3, seen its ability on snow, on a steep drive up to the family croft. Clearly a hand's off approach, ABS/DSC is in control, you can clearly see what it's doing, if you stand and watch.

What is beyond dispute about xDrive, it is regulating drive torque (forward traction) to the appropriate wheels on acceleration. I've trawled through all the xDrive data I have access to, and never found specifics on how the system works on the over-run, or engine braking. The critical bit will be how the transfer clutch works and is regulated, to balance the grip between the axles during braking, assisting individual wheel grip levels. No mention of this in BMW technical data. If the clutch opens, (as it does in some situations, like slow speed tight cornering), then all bets are off to how xDrive assists deceleration. What we do know ABS takes control under slip conditions during braking.

We also know, braking alone can use all the grip available, doesn't require engine braking to stop the vehicle. OK, there are times when engine braking retards the car, but "what axles are doing what?" in xDrive vehicles. With RWD we know it is the rear that is using engine braking, leaves the front tyres for modulating the speed of deceleration using braking, or in other words, under the driver's command and control.

An example is in snow. I'm suspicious of how xDrive assists stopping through engine braking. RWD it is clear, engine braking gives control of the rear, separate from the brake pedal. Can allow sensitive modulation of the brakes to retard and control front end slip. You know you have two control systems, either separate, or together, working under the driver's control.

If anyone has reference to how xDrive 'transfer' works under braking... if it does... most interested to understand its function.
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      08-17-2018, 09:38 AM   #74
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Quote:
Originally Posted by HighlandPete View Post
There is a big difference in slow speed control, than decelerating from high speed.

We've used the descent control (hill assist) in my son's X3, seen its ability on snow, on a steep drive up to the family croft. Clearly a hand's off approach, ABS/DSC is in control, you can clearly see what it's doing, if you stand and watch.

What is beyond dispute about xDrive, it is regulating drive torque (forward traction) to the appropriate wheels on acceleration. I've trawled through all the xDrive data I have access to, and never found specifics on how the system works on the over-run, or engine braking. The critical bit will be how the transfer clutch works and is regulated, to balance the grip between the axles during braking, assisting individual wheel grip levels. No mention of this in BMW technical data. If the clutch opens, (as it does in some situations, like slow speed tight cornering), then all bets are off to how xDrive assists deceleration. What we do know ABS takes control under slip conditions during braking.

We also know, braking alone can use all the grip available, doesn't require engine braking to stop the vehicle. OK, there are times when engine braking retards the car, but "what axles are doing what?" in xDrive vehicles. With RWD we know it is the rear that is using engine braking, leaves the front tyres for modulating the speed of deceleration using braking, or in other words, under the driver's command and control.

An example is in snow. I'm suspicious of how xDrive assists stopping through engine braking. RWD it is clear, engine braking gives control of the rear, separate from the brake pedal. Can allow sensitive modulation of the brakes to retard and control front end slip. You know you have two control systems, either separate, or together, working under the driver's control.

If anyone has reference to how xDrive 'transfer' works under braking... if it does... most interested to understand its function.
And not to forget that most of the xdrive cars are diesel, which has much less engine braking than a petrol engine.
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      08-17-2018, 09:39 AM   #75
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Quote:
Originally Posted by Drew474 View Post
If the next gen 3/4 series 40i cars have an xdrive option, that’s when I’ll move to the petrol.

I won’t buy a bmw without xdrive now I have lived with it for years. I don’t require the ability to drift round corners.
Most of us don't have the ability either, but not sure how relevant that is to the discussion!
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      08-17-2018, 09:42 AM   #76
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Quote:
Originally Posted by JustChris View Post
X Drive thread. Guaranteed 10 pager on UK section

I think realistically AWD vehicles will be the norm on all but entry level brands. I'll be pretty surprised if the new M3/4 isn't the same as the F90 now with how well it's been received.

Performance S Drive type cars will be becoming collectors items pretty soon.
Makes for good debates...

A few years ago we didn't really require xDrive in the UK, (according to BMW) other than X models. How a generation of cars can change the marketplace.

Can't even replace my car with a like model now, without going xDrive, isn't an option. Not to say that's a bad thing, well specced G31 540i xDrive on winter tyres will be a excellent all-weather vehicle.
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      08-17-2018, 09:48 AM   #77
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Originally Posted by Tengocity View Post
And not to forget that most of the xdrive cars are diesel, which has much less engine braking than a petrol engine.
Good point, plus with autos, how many drivers will consciously control any engine braking? More likely jab the brakes and be confused as to why the revs have suddenly gone up, and the car is trying to slow on its own.
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      08-17-2018, 09:48 AM   #78
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Quote:
Originally Posted by JustChris View Post
I think realistically AWD vehicles will be the norm on all but entry level brands. I'll be pretty surprised if the new M3/4 isn't the same as the F90 now with how well it's been received.

Performance S Drive type cars will be becoming collectors items pretty soon.
I can possibly see a move towards AWD for very high performance vehicles but I see no reason why it should become the norm generally. For most cars and drivers 2wd - whether FWD or RWD - is perfectly adequate and for them 4WD will just mean additional unnecessary weight and inferior fuel consumption.

In very high powered cars AWD probably offers a bit of a safety net but, as has been said earlier, in some respects it also perhaps serves to cover-up shortcomings with the driver which gives them a false sense of security and aura of invincibility; net result is the potential accident just happens at a higher speed!
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      08-17-2018, 09:59 AM   #79
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Quote:
Originally Posted by HighlandPete View Post
Good point, plus with autos, how many drivers will consciously control any engine braking? More likely jab the brakes and be confused as to why the revs have suddenly gone up, and the car is trying to slow on its own.
Funny you should say that Pete, but when I bought the Boxster a couple of years ago I had to almost re-learn the "technique", after years of diesels and autos.

I had some very good instruction on a track day last year around it and how to use heel/toe braking to maximise it's benefits to help the brakes. Very demanding to do and get right (which I often didn't), but also very rewarding.
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      08-17-2018, 10:09 AM   #80
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Seen plenty of BMWs passing me on the M8 way above safe driving limit. Accidents are sometimes the fault of the driver.
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      08-17-2018, 10:39 AM   #81
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Originally Posted by Tengocity View Post
I had some very good instruction on a track day last year around it and how to use heel/toe braking to maximise it's benefits to help the brakes. Very demanding to do and get right (which I often didn't), but also very rewarding.
Indeed so, IMHO there's a challenge and reward - and as a consequence a sense of involvement - with a manual which you simply don't get with an auto. That's not to say an auto doesn't offer a faster and more consistent change - most of the time it does which is what makes them so good as daily drivers - but for me a manual wins hands-down for fun and engagement.

No doubt makes me a dinosaur in the eyes of some (many?) but each to their own!
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      08-17-2018, 11:04 AM   #82
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Quote:
Originally Posted by Ajs_435d View Post
Quote:
Originally Posted by teaston View Post
Xdrive is all wheel drive.

All wheel drive is technically superior to 2 wheel drive in every single way, The only drawbacks are extra cost of manufacturing and slightly lower efficiency on the smaller underpowered engines. Why you'd make such a nonsense statement is beyond me.
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Because you've missed the sarcasm in my post - look at what model I own!
Oh you need to use a when you're being sarcastic.
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      08-17-2018, 11:11 AM   #83
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Quote:
Originally Posted by HighlandPete View Post
Quote:
Originally Posted by teaston View Post
I'm sure they are great in the dry, but a road car has to work in all conditions, which rwd just doesn't.
What I think you are saying, xDrive can take more abuse from the driver in many circumstances, like being more accommodating for erratic load transfer. If that makes it a better chassis, I won't disagree, it is a good thing.

I'll put a flame suit on for this comment... can to a degree make up for less driver precision and to be frank, driver ability. Problem is, some drivers are assuming xDrive (AWD, 4WD) makes them invincible in more difficult conditions and/or push the limits, often more than is safe to do when tyre grip is the limiting factor.
Yes it can help lesser ability drivers, but mainly I mean the performance gains that it gives in the wet/damp/cold when RWD would struggle for grip no matter how good a driver you are.
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      08-17-2018, 11:15 AM   #84
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If you live in California and drive to the mountains in the winter, all-wheel drive or 4-wheel drive is a must-have. If you are an idiot, you cannot drive in snow no matter what kind of drive, and if you know how to drive, you can use RWD with a little bit of snow. HOWEVER, if you don't have AWD/4WD, the Highway Patrol will stop you and won't let you go through even if there is just a dusting of snow. There is also a law that during the winter, you cannot drive in the mountains without carrying chains or having AWD/4WD.
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      08-17-2018, 11:22 AM   #85
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Quote:
Originally Posted by teaston View Post
Yes it can help lesser ability drivers, but mainly I mean the performance gains that it gives in the wet/damp/cold when RWD would struggle for grip no matter how good a driver you are.
But in the wet/damp/cold AWD doesn't offer any more lateral grip and won't stop you any faster; it offers some traction advantages on acceleration but that's all.

I can't say I've ever had a significant problem in relatively powerful RWD cars (E46 M3, E92 335i, etc) in those sort of conditions, a little more care with the right foot is all that's required!
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      08-17-2018, 11:43 AM   #86
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Yes it can help lesser ability drivers, but mainly I mean the performance gains that it gives in the wet/damp/cold when RWD would struggle for grip no matter how good a driver you are.
There is no doubt, xDrive does give many advantages, but question judging it on performance gains alone. I suppose the bigger picture is, are we really needing the higher performance, or can we safely use it, in typical driving on public roads?

Arguing that we are protecting or enhancing our own safety, is a bit of a red herring. (Although I don't think anyone is against having a greater safety window). If we are simply moving the performance abilities to a higher risk area, we have to question the benefit. We can still fall foul to accidents, may be even more severe when they happen.

This applies to using any 'added' performance, so easy to impinge on the safety of other road users. We still must look for the lowest common denominator. xDrive may enhance our safety in some circumstances, same as better brakes and tyres may do. But as we've mentioned in the topic on motorway driving, we may be able to stop better with high performance brakes, but the next guy has to be allowed for, will he hit us up the rear in the same circumstance? We may have to moderate our driving to really be safer.

"Driving to the conditions" is still our greatest safety asset.
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      08-17-2018, 11:50 AM   #87
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But in the wet/damp/cold AWD doesn't offer any more lateral grip and won't stop you any faster; it offers some traction advantages on acceleration but that's all.
True, we have to keep that in mind.

As put forward in a previous post, we only have a finite amount of grip on a given set of tyres. If we use more of the available grip for drive torque (traction) there is less for steering, braking and stability.
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      08-17-2018, 12:00 PM   #88
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Quote:
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Quote:
Originally Posted by teaston View Post
Yes it can help lesser ability drivers, but mainly I mean the performance gains that it gives in the wet/damp/cold when RWD would struggle for grip no matter how good a driver you are.
But in the wet/damp/cold AWD doesn't offer any more lateral grip and won't stop you any faster; it offers some traction advantages on acceleration but that's all.

I can't say I've ever had a significant problem in relatively powerful RWD cars (E46 M3, E92 335i, etc) in those sort of conditions, a little more care with the right foot is all that's required!
So, it could be reasonably argued that sDrive is actually the safer system in most situations...

xDrive allows unthinking acceleration without challenging the skill of the driver. So, the normal driver could easily find the self traveling beyond the limit of their true skill level...

The electrical systems of my car nanny/flatter me massively. However, if I over do it a bit, the back end reminds me. Though, my 330d sDrive stepped out unexpectedly much more often than my present 340i sDrive does. Given my modest skill level the petrol output delivery is less torque based and easier to modulate.
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