All wheel drive vs 4 wheel drive vs ?

The following is from the current UK Defender brochure:

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ALL WHEEL DRIVE (AWD)
Compelling performance. Off and on road. The system intuitively controls the torque distribution between the front and rear axle. On challenging surfaces, such as sand, grass or snow, torque can be balanced between the front and rear wheels to maximise traction. In extreme conditions, where the front or rear wheels lose traction, 100 percent of engine torque can be distributed to the opposite axle for optimum grip. Our Intelligent AWD System* takes this even further
by allowing variable torque distribution, resulting in a more precise and dynamic on-road performance and higher torque capacity – all without sacrificing any of Defender’s inherent off-road capability.


*D200, D250 and D300 6-cylinder Diesels only.

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Which is what I would expect. It has been a long time since I drove a 4WD that sent drive to wheels without traction.

LR are just doing it slightly differently than the usual traction control method of distributing torque.

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Originally Posted by JessicaTam

The following is from the current UK Defender brochure:


Which is what I would expect. It has been a long time since I drove a 4WD that sent drive to wheels without traction.

LR are just doing it slightly differently than the usual traction control method of distributing torque.

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Yes I shouldn't be distracted by my current crusade, namely, bringing JLR to account with regards to its sales pitch.

My original question also seeks to understand the real-world ramifications of the engineering decision that has been taken by JLR. So far we are dealing with "black box" not "open source". That concerns me as much as anything else.

I'm keen to get feedback on the performance on and off road of the AWD system from users.

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Originally Posted by one_iota

Thanks TB. Your devil's advocacy is helpful.

Given that two dealerships have offered contradictory advice I can now escalate this to JLR Australia Head Office to demonstrate that, at best, its dealerships don't know the product they are selling!

Stay tuned.

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I've had a positive response from Head Office to its credit. It has been formally raised as an issue to be resolved. (It even has a number!)

Translation from marketing-speak:

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Compelling performance. Off and on road.

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"This is a Land Rover that's nice to drive."

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The system intuitively controls the torque distribution between the front and rear axle. On challenging surfaces, such as sand, grass or snow, torque can be balanced between the front and rear wheels to maximise traction. In extreme conditions, where the front or rear wheels lose traction, 100 percent of engine torque can be distributed to the opposite axle for optimum grip.

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"We do real 4WD systems, not a dinky AWD that can't deal with a bit of wheel slip."

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Our Intelligent AWD System* takes this even further by allowing variable torque distribution, resulting in a more precise and dynamic on-road performance and higher torque capacity – all without sacrificing any of Defender’s inherent off-road capability.

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"We've done something weird and hard to explain on the new diesels, but trust us it's awesome! When you're off-road it's sorta like an old Series LR except instead of having to pick between 2WD and 4WD the computer can kinda blend in between them when it thinks the front wheels need to help you along. And on-road it's like our cool Jag sports cars (because that's the same system we've put in here)!"

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Originally Posted by JessicaTam

LR are just doing it slightly differently than the usual traction control method of distributing torque.

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Slight disagree here. Terrain Response's traction control software is still doing left/right torque management via braking on the front axle and also on the rear if you have the open diff there. If you have the rear locking diff then you get "torque vectoring by braking" on the rear to assist with turns also (this is actually awesome off-road and I don't think it gets called out enough). Those statements apply to both the familiar permanent AWD system with the centre locking diff and the new Jag-sourced system with the clutch-only connection for the front drive shaft. It's those transfer case mechanisms, not traction control, that are responsible for front/rear torque management.

Couple of updated thoughts from me.

First thanks for the discussion. I didn't dive into this with an aim to make trouble, I do it to try and understand things that LR's own materials do a **** job of explaining. As we've worked through it over time I actually feel more relaxed about the new system because my initial questions have gradually found reasonable answers.

The words "higher torque capacity" from JessicaTam's post just now are potentially important. The new diesels are pretty torquey. Maybe the old locking centre diff finds it hard to cope? Maybe a big clutch taking up the available space can more reliably direct all that torque to the front when needed? That would be a clear engineering benefit of the new system.

Learning that this system comes from the Jaguar side also helps understand the way it's tuned, and this will be particularly relevant on fast dirt and gravel, even some bitumen. I think the permanent AWD via a centre diff is probably still better in terms of overall traction... though perhaps not by much. But I have no doubt the Jag system would be more fun, because it's literally designed to pull you through corners in oversteer!

And off road it's got all the capability of "part-time 4WD" systems (which is to say, a lot) plus the flexibility to relax the front drive while turning if rear traction isn't a problem.

So: slightly improved fuel economy, potentially better handling of high torque engines, likely more fun on the twisty bits... in exchange for losing a little bit of sure-footedness and possibly increasing tyre wear.

Like Mr Iota, I'm looking forward to hearing from owners of I6 diesels how their new Defenders go. Enjoy!

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Originally Posted by TB

The words "higher torque capacity" from JessicaTam's post just now are potentially important. The new diesels are pretty torquey. Maybe the old locking centre diff finds it hard to cope? Maybe a big clutch taking up the available space can more reliably direct all that torque to the front when needed? That would be a clear engineering benefit of the new system

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Could be to reduce torque-steer.

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Originally Posted by one_iota

I've had a positive response from Head Office to its credit. It has been formally raised as an issue to be resolved. (It even has a number!)

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I have received a reply from JLR Australia's Customer Relations Centre and I quote the substance of that reply.

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Regarding your question on the AWD system, the footnote mentioned is correct and is relevant to Diesel powertrains which is D200, D250 and D300.

These have the intelligent driveline and offer a variable torque split front to rear.


The system can vary the distribution of the front/rear torque split, continuously monitoring the environment and driver inputs to optimise capability, composure, and efficiency.The new driveline can reduce driveline losses by 30% and improve CO2 emissions by more than 4 g/km while the ability to vary the torque split front to rear also supports optimised on-road handling and driving dynamics.

Typically, the system will vary the torque distribution from Rear to Front for efficient operation up to 50:50 when traction is a priority. The control is monitoring steering, vehicle acceleration and wheel speeds to optimise the response of the vehicle for the prevailing terrain to improve vehicle composure and reduce driver workload. For more extreme off-road driving such as rock crawl the centre coupling is locked to transmit more of the drive torque to the axle with the most available traction.

The control is linked to the vehicle Terrain Response functions and is designed to replicate the torque distribution of the existing driveline when traction is compromised.


In addition, the system has a gradient sensing function to ensure optimum torque distribution when descending steep slopes off-throttle to enhance Hill Descent Control performance.

The system has been engineered and tested to the same rigorous standards applied to all Land Rover drivelines and delivers customary Defender capability with enhanced efficiency.

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Originally Posted by one_iota

I have received a reply from JLR Australia's Customer Relations Centre and I quote the substance of that reply.

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Good stuff - thanks!

Activating my marketing-speak decoder...

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Regarding your question on the AWD system, the footnote mentioned is correct and is relevant to Diesel powertrains which is D200, D250 and D300. These have the intelligent driveline and offer a variable torque split front to rear.

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The new diesels don't have a centre diff any more.

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The system can vary the distribution of the front/rear torque split

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The front wheels aren't always driven.

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continuously monitoring the environment and driver inputs to optimise capability, composure, and efficiency.

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But it's not a dumb part-time 4WD either. The Terrain Response computer decides when the drive the front wheels just like the earlier system decided when to lock the centre diff.

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The new driveline can reduce driveline losses by 30% and improve CO2 emissions by more than 4 g/km

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The latest emissions standards are really fricking tough to meet and we're chasing down every damn g/km.

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while the ability to vary the torque split front to rear also supports optimised on-road handling and driving dynamics.

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Oversteer is fun! We can do it deliberately now!

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Typically, the system will vary the torque distribution from Rear to Front for efficient operation up to 50:50 when traction is a priority.

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RWD when we can get away with it, only driving the front wheels when we have to.

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The control is monitoring steering, vehicle acceleration and wheel speeds to optimise the response of the vehicle for the prevailing terrain to improve vehicle composure and reduce driver workload. For more extreme off-road driving such as rock crawl the centre coupling is locked to transmit more of the drive torque to the axle with the most available traction.

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We have a 4WD function that works in the usual way.

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The control is linked to the vehicle Terrain Response functions and is designed to replicate the torque distribution of the existing driveline when traction is compromised.

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We don't trust the market to understand what we've done so we're doing a lot of hand waving and trying to reassure you that you won't notice any difference. Except for the oversteer bit – which is awesome right!?

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In addition, the system has a gradient sensing function to ensure optimum torque distribution when descending steep slopes off-throttle to enhance Hill Descent Control performance.

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We even remembered that the front wheels need to be connected to the engine for engine braking to work well downhill.

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The system has been engineered and tested to the same rigorous standards applied to all Land Rover drivelines and delivers customary Defender capability with enhanced efficiency.

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Please stop asking questions. It's a Land Rover. We can sell it because we snuck the CO2 emissions below the Euro limit and we really hope you'll be satisfied with all these superlatives.

Now that these vehicles are arriving in people's garages we've learned some things, and one of those is something we should make sure everybody understands for safety reasons.

When a six-cylinder diesel Defender is parked, the front wheels are independent and unrestrained. The front driveshaft is disconnected from the rear, the right front wheel is disconnected from the front differential, and there are no parking brakes on the front.

So you are 100% relying on the rear wheels to prevent any rolling or sliding. The rear wheels are permanently connected to each other and the transmission via the rear differential so they have both the gearbox parking pawl and the park brakes restraining them.

The safety factor here is related to parking on any steep or slippery incline, and to jacking the vehicle up. Unlike all other modern LRs with permanent AWD, or older LRs with 4WD engaged, when you jack up a corner on one of these six-cylinder diesel Defenders you will not have the three other corners preventing movement: you will have only the rear wheels and potentially just one of them if it's a rear corner that you've lifted. If you lift a front corner you'll be able to spin that wheel freely.

It would be a very good idea for owners of these vehicles to add some sturdy wheel chocks to their kit.

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Originally Posted by TB

Now that these vehicles are arriving in people's garages we've learned some things, and one of those is something we should make sure everybody understands for safety reasons.

When a six-cylinder diesel Defender is parked, the front wheels are independent and unrestrained. The front driveshaft is disconnected from the rear, the right front wheel is disconnected from the front differential, and there are no parking brakes on the front.

So you are 100% relying on the rear wheels to prevent any rolling or sliding. The rear wheels are permanently connected to each other and the transmission via the rear differential so they have both the gearbox parking pawl and the park brakes restraining them.

The safety factor here is related to parking on any steep or slippery incline, and to jacking the vehicle up. Unlike all other modern LRs with permanent AWD, or older LRs with 4WD engaged, when you jack up a corner on one of these six-cylinder diesel Defenders you will not have the three other corners preventing movement: you will have only the rear wheels and potentially just one of them if it's a rear corner that you've lifted. If you lift a front corner you'll be able to spin that wheel freely.

It would be a very good idea for owners of these vehicles to add some sturdy wheel chocks to their kit.

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You are correct, but I wonder how many people were aware of the same safety issue with their classic RR's and Defenders. There was a reason LR packed a wheel chock with the tool kit. m