[Abrek]

So driving home today, regular commute - Glasgow to Edinburgh, started to rain as I was leaving Glasgow. Road conditions were so-so, some standing water but nothing too horrendous but I had adjusted my driving accordingly. Couple of miles in to my drive noticed the car in front stopped suddenly. I had a bit of "oh shit! moment" but m sport brakes did their job. The reason for the stop is that looked like single car(BMW) accident, driver lost it on wet road and span a few times with a few impacts in to the barriers. The driver was in a bad state but conscious but visibly in shock. It's not a first time in the last couple of months that I have seen BMW in the barriers on the M8.

Makes me wonder if the car had an Xdrive it could have helped prevent the crash but it's hard to know without knowing all details. But moments like this make me appreciate the fact that my car has one.

Anyway this is a video from my dashcam, not the best but you can see the results.

[Wills2]

Not really, xdrive gives no better grip and therefore no better braking performance and no better resistance to aquaplaning, it does give better traction which generally just allows you to get to your accident quicker.

[Tengocity]

I'd say tyres make a bigger difference than anything else in these types of situations.

[Rbrown]

I would also say tyres. Winter tyres do help when the weather turns and heavy rain. A bit like today!

[Hooded]

Agree.. tyres make a difference in the situation you describe .. xdrive doesn't

[Abrek]

Fair enough. In my head I thought xdrive would help to regain control quicker. I agree that tyres probably be the biggest factor, although for the age of that car I would be surprised if they were not in a good condition but we will never know.

[robbiep]

Tyres, driver competence and judgement (appropriate speed, reading the conditions, etc, etc), a load of other factors ... eventually, a long way down the list of avoiding factors, xDrive.

[Tengocity]

Originally Posted by Abrek

Fair enough. In my head I thought xdrive would help to regain control quicker. I agree that tyres probably be the biggest factor, although for the age of that car I would be surprised if they were not in a good condition but we will never know.

Can't see the video so not sure how old the car in question is, but my 330e company car is 2 years old, but has done 50k miles, but only just changed the rear tyres. For the last 10k miles it only had 2mm on the inner edge, and 3ish over the rest of the width. If it was my car I'd have replaced the tyres 10k miles ago, but as it's leased the lease company won't do it till it's below 2mm!

So when there was lots of standing water around I slowed down a lot more in that car than in our other cars which we all own, and which all have good tyres.

So it's not always easy to know what's really the situation.

[Smee]

sorry to those say Xdrive wouldnt help. can some one explain your theory here because i would beg to differ.

[NISFAN]

Originally Posted by Smee

sorry to those say Xdrive wouldnt help. can some one explain your theory here because i would beg to differ.

Haven't you seen an Audi Quattro ad.?

[330XDave]

It's only going to help if putting the power down will in some way help you recover from a spin which is highly unlikely. Chances are you wouldn't even have time to react. xDrive is all about traction when the power is being put through the wheels.

Plus haven't you heard? Not sure if anyone has mentioned this but apparently it drives like a hearse with xDrive fitted...

[4WDriver]

Originally Posted by Smee

sorry to those say Xdrive wouldnt help. can some one explain your theory here because i would beg to differ.

When you press the brake pedal the number of driven wheels becomes totally irrelevant. As has been said, AWD might get you up to the wrong speed more quickly at which point..... Panic, brake, crash.

Had the driver been able to power and steer through any initial skid then the outcome might have been helped by AWD but that takes balls and experience rarely seen on the public highway. And I did say might!

Same applies in snow and/or ice.

[Richard52]

Originally Posted by Tengocity

Can't see the video so not sure how old the car in question is, but my 330e company car is 2 years old, but has done 50k miles, but only just changed the rear tyres. For the last 10k miles it only had 2mm on the inner edge, and 3ish over the rest of the width. If it was my car I'd have replaced the tyres 10k miles ago, but as it's leased the lease company won't do it till it's below 2mm!

So when there was lots of standing water around I slowed down a lot more in that car than in our other cars which we all own, and which all have good tyres.

So it's not always easy to know what's really the situation.

Don't want to be dramatic - it's not your car but it is your life !!!

[Tengocity]

Originally Posted by Richard52

Don't want to be dramatic - it's not your car but it is your life !!!

Yeah, that's why I palm that car off to Mrs Tengocity and I use the M4... much safer!

[JustChris]

Not for me.

Safer in some regards but in no means essential.

[KCH1984]

Originally Posted by Smee

sorry to those say Xdrive wouldnt help. can some one explain your theory here because i would beg to differ.

+1

As I drive that motorway regularly myself I would say 100% that in those conditions my 330d xDrive felt far more secure than my M135i ever did.

I get the point about lateral grip but take 2 330d's for example, in the RWD car all the power and torque is going through the back axle whereas in the AWD car it is being spread across 4 driven wheels. Therefore, surely the chances of overwhelming the available grip from the tyres (as less torque is going through any one wheel) is less overall? It would seem to me the type of accident mentioned is a result of the rear tyres being overwhelmed in poor conditions resulting in a loss of control, much in the same way as the dramatised top gear vid with Clarkson in the M135i.

EDIT: I'm looking at this from a preventative angle as I appreciate that once the accident has begun, the xDrive isn't a magical get out of jail free card.

[TouringPleb]

Originally Posted by robbiep

Tyres, driver competence and judgement (appropriate speed, reading the conditions, etc, etc), a load of other factors ... eventually, a long way down the list of avoiding factors, xDrive.

This

[TouringPleb]

Originally Posted by Wills2

Not really, xdrive gives no better grip and therefore no better braking performance and no better resistance to aquaplaning, it does give better traction which generally just allows you to get to your accident quicker.

Aren't grip and traction the same thing?

[Tengocity]

The question in the title is whether it's a must have... simple answer is no.

I wouldn't say there is no benefit... i very much liked having xdrive, and plenty times it was a benefit.

[Tengocity]

Originally Posted by TouringPleb

Aren't grip and traction the same thing?

Not really.

Traction is the ability get the power done and translated in to forward motion.

Grip is what stops you sliding off the road as you turn, brake etc.

You need grip for traction, but not the exact same thing.

Xdrive helps traction massively, especially in the wet, but it doesn't produce more grip.

[TouringPleb]

Originally Posted by Tengocity

Not really.

Traction is the ability get the power done and translated in to forward motion.

Grip is what stops you sliding off the road as you turn, brake etc.

You need grip for traction, but not the exact same thing.

Xdrive helps traction massively, especially in the wet, but it doesn't produce more grip.

I'm confused..

[Alice Coupe]

xDrive certainly has its place. However, judging by the speed of that Silver Corsa? at 1:32, there’s the reason for your accident right there. At that speed in those conditions any swerve will put you in a spin. The driver may have had a blow out, there may have been debris on the road, someone brakes to slow rather than just taking their foot of the gas, driver behind panics and spins etc.

I just don’t get those that drive the same way in rain hail or snow as they do in the dry.