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Hey Stompe,

I think the take rate on the E4 system here in the UK is pretty small. We just don't get the weather, and according to the official specs it has a noticeable cost in terms of fuel economy. I seriously considered it for my next UX, but in the end was talked out of it by my partner. The fact is, if the road conditions are so bad that snow tyres cannot get you out, then adding driven rear wheels isn't going to help a massive amount.

My advice would be to save your money, get the FWD version, and then invest in a set of snow tyres for your winter travels.

Nick

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Doesn't the AWD system contribute toĀ makingĀ the already small boot even smaller by further reducing the depth? (which makes me wonder if the 2WD version of the NX has a deeper boot that the AWD!...)

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16 minutes ago, DanD said:

Doesn't the AWD system contribute toĀ makingĀ the already small boot even smaller by further reducing the depth? (which makes me wonder if the 2WD version of the NX has a deeper boot that the AWD!...)

It does but it really doesn't seem to be as big of an issue as the specification makes out:

Ā 

The NX boot capacity isn't changed whether you have 2WD or AWD.

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On 8/11/2021 at 5:25 PM, EvilRacer329 said:

Hey Stompe,

I think the take rate on the E4 system here in the UK is pretty small. We just don't get the weather, and according to the official specs it has a noticeable cost in terms of fuel economy. I seriously considered it for my next UX, but in the end was talked out of it by my partner. The fact is, if the road conditions are so bad that snow tyres cannot get you out, then adding driven rear wheels isn't going to help a massive amount.

My advice would be to save your money, get the FWD version, and then invest in a set of snow tyres for your winter travels.

Nick

Spot on. A 2WD car with winter tyres will out perform a 4WD car without winter tyres. In wintry conditions of course!

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The fun part is that while four-wheel-drive might help get you going in slipper conditions, it can't help you turn or stop. Winter tyres help in *all* situations. šŸ˜‰

Nick

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20 hours ago, paulrnx said:

A 2WD car with winter tyres will out perform a 4WD car without winter tyres. In wintry conditions of course!

It doesn't have to be one or the other. An AWD with winter tyres would be even better. It also provides better traction during the months of using summer tyres when roads become slippery e.g. when it first starts to rain after a long dry spell.

AWD isn't just about traction either, the stability control system uses it to counteract under/over steer.Ā But unfortunately on the UX the extra motor doesn't provide any additional power/performance.

Clearly it's a decision based on personal priorities. Myself, I didn't feel the advantages outweigh the disadvantages (cost, economy, boot space) so went with a 2WD variant, and it seems the vast majority feel the same as less than 5% of all UK UXs are AWD variants.

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You're 100% correct; I almost went with the 4WD option because I hoped it would help improve cornering by counteracting understeer, but in the end I couldn't find any confirmation online that it actually worked as I'd hope. And I wasn't willing to take the disadvantages and extra cost on board to find out.

Nick

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56 minutes ago, ColinBarber said:

It doesn't have to be one or the other. An AWD with winter tyres would be even better. It also provides better traction during the months of using summer tyres when roads become slippery e.g. when it first starts to rain after a long dry spell.

AWD isn't just about traction either, the stability control system uses it to counteract under/over steer.Ā But unfortunately on the UX the extra motor doesn't provide any additional power/performance.

Clearly it's a decision based on personal priorities. Myself, I didn't feel the advantages outweigh the disadvantages (cost, economy, boot space) so went with a 2WD variant, and it seems the vast majority feel the same as less than 5% of all UK UXs are AWD variants.

The only true AWD NX is the 200T Iā€™d have thought. MostĀ others are marketed as AWD on account of having the extra electric motor driving the rearĀ wheels. Must admit I thought it was way more than 5%. All NX Luxury variants have AWD or at least I thought they did. Maybe not?

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35 minutes ago, EvilRacer329 said:

You're 100% correct; I almost went with the 4WD option because I hoped it would help improve cornering by counteracting understeer, but in the end I couldn't find any confirmation online that it actually worked as I'd hope. And I wasn't willing to take the disadvantages and extra cost on board to find out.

Some of the 4WD drive trains these days are part time 4WD for fuel efficiency reasons. This however means that when they engage the 4WD due to weather conditions, it can lead to unpredictable handling. See the Haldex systems for instance.

I wouldn't personally trust any such automatically system myself, which is why my previous 4WD cars were all full time 4WD (Subaru Legacy, Celica GT4).

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21 minutes ago, paulrnx said:

The only true AWD NX is the 200T Iā€™d have thought. MostĀ others are marketed as AWD on account of having the extra electric motor driving the rearĀ wheels. Must admit I thought it was way more than 5%. All NX Luxury variants have AWD or at least I thought they did. Maybe not?

This thread is about the UX.

What does 'true' AWD mean? The hybrids with rear motors are AWD, they can drive all wheels.

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1 hour ago, EvilRacer329 said:

You're 100% correct; I almost went with the 4WD option because I hoped it would help improve cornering by counteracting understeer, but in the end I couldn't find any confirmation online that it actually worked as I'd hope. And I wasn't willing to take the disadvantages and extra cost on board to find out.

Nick

E-FOUR ALL WHEEL DRIVE

The UX 250h is available with either front-wheel drive or E-Four electric all-wheel drive.

The E-Four all-wheel drive system uses a separate, dedicated high-torque electric motor integrated into the rear differential. Power distribution between the front and rear axles is automatically optimised by the Vehicle Stability Control (VSC) system when accelerating, cornering, or driving on slippery surfaces. E-Four provides stable driving on uphill slopes or snow-covered roads with lower fuel consumption than a conventional all-wheel drive system with a power split device and driveshaft. E-Four does more than assist traction in slippery conditions: it can also actively improve stability by adjusting rear-wheel power to help correct over or understeer.

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The key difference, as I understand it, is whether a four-wheel-drive system is proactive or reactive; does it wait for the front to lose traction before reluctantly adding power to the rears, or is it driving all four wheels continuously so that the aforementioned loss of traction doesn't occur in the first place? The system in the UX is the former, whereas Subaru's system and other performance-oriented AWD systems are the latter. But as you say, the fuel economy trade-off in driving four wheels through three differentials is pretty staggering, and the Lexus solution is very clever and would work well in certain circumstances.

Nick

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40 minutes ago, EvilRacer329 said:

The key difference, as I understand it, is whether a four-wheel-drive system is proactive or reactive; does it wait for the front to lose traction before reluctantly adding power to the rears, or is it driving all four wheels continuously so that the aforementioned loss of traction doesn't occur in the first place? The system in the UX is the former, whereas Subaru's system and other performance-oriented AWD systems are the latter. But as you say, the fuel economy trade-off in driving four wheels through three differentials is pretty staggering, and the Lexus solution is very clever and would work well in certain circumstances.

Nick

That's almost the difference between 4WD and AWD. Hardly any current-day road car AWD system provides power to front and rear in any sort of equal measure, it reacts to a loss before shifting the power.

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On 8/13/2021 at 8:36 PM, ColinBarber said:

This thread is about the UX.

What does 'true' AWD mean? The hybrids with rear motors are AWD, they can drive all wheels.

Oops. My mistake

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On 8/13/2021 at 10:00 PM, ColinBarber said:

That's almost the difference between 4WD and AWD. Hardly any current-day road car AWD system provides power to front and rear in any sort of equal measure, it reacts to a loss before shifting the power.

Probably; I'll admit that my knowledge of such systems is limited to more enthusiast-oriented applications. Most of those are geared to deliver a constant torque split, e.g. 70% rear, 30% front. That way, if the rear slips for whatever reason the fronts can pick up the slack instantly without waiting for a computer to figure things out. Then you get the hardcore 4x4 systems with locking diffs etc. that are actually not recommended to use in that mode on regular roads because they have no slip built in whatsoever.

In a perfect world, Lexus would've designed the UX's E-Four system to be turning the rear wheels with electric power any time the vehicle was moving, and use vehicle roll and yaw sensors to pre-emptively load the necessary wheel to increase oversteer/decrease understeer. Maybe that's exactly what they did! But I've not found a single review that drills down into that level of detail because, well, most enthusiasts wouldn't buy a UX to begin with. I'm one of those outliers that enjoys performance driving, but also values built quality, comfort, reliability, and fuel economy. I also value the option ofĀ notĀ driving around like my hair's on fire and just relaxing, hence I love the hybrid system.

Nick

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On 8/15/2021 at 10:46 AM, EvilRacer329 said:

In a perfect world, Lexus would've designed the UX's E-Four system to be turning the rear wheels with electric power any time the vehicle was moving, and use vehicle roll and yaw sensors to pre-emptively load the necessary wheel to increase oversteer/decrease understeer. Maybe that's exactly what they did!

They didn't fully do that, but then it isn't needed for what they are trying to achieve (this isn't a true off-road vehicle or a rally car) and the electric motor can start to deliver power within a fraction of a second when the system determines it needs to.

When you pull away, depending on the amount of throttle and if the vehicle is on a slope,Ā it will use the rear motor (to varying degrees)Ā to aid traction. Outside of that the system is reactiveĀ based on the wheel sensors, yaw sensor andĀ steering wheel angle.

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I highly recommend the latest 4 wheel drive linked to AVS works perfectly on twisty backroads for example.

Without consulting the Bible there are many instances when the rear drive engages since the 2018 Revision on the NX.

When the Boss & I decided to have only one car we choose a 4x4 UX with AVS but, despite my Dealer saying there was availability en-route to the UK,it was not true & Lexus GB claimed a 6 month wait.

I cancelled &; 6 months later purchased a 2021 NX which is better than the 2019 version & cheaper financially.

Tel

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