[xcountry]

Hi All,

I have a X7 on order via PCD delivery that among many other options, includes Integral Active Steering (IAS).

I haven't test driven a X7, only a X5 and not sure whether it was with or without IAS so could someone who has actually driven the X7 with and without the IAS explain the experience of having IAS?

I know that theoretically the rear wheels turn in one direction at low speeds and a different direction at high speeds, but I am looking for a more practical "what you experience" and "what you actually get" insight. Thanks.

Regards,
sjwr

[Auricom]

Originally Posted by sjwr

Hi All,

I have a X7 on order via PCD delivery that among many other options, includes Integral Active Steering (IAS).

I haven't test driven a X7, only a X5 and not sure whether it was with or without IAS so could someone who has actually driven the X7 with and without the IAS explain the experience of having IAS?

I know that theoretically the rear wheels turn in one direction at low speeds and a different direction at high speeds, but I am looking for a more practical "what you experience" and "what you actually get" insight. Thanks.

Regards,
sjwr

There are two parts to "what you experience" and "what you actually get" question

TL;DR

What you experience - it's all in the steering
What you experience varies for different drivers - some may notice the variable steering ratio changes (direct / indirect steering feel) and others don't notice the change but sense that during turns steering wheel travel / feel's reduced or elongated. I'm in later category in regards to steering. Otherwise, you're not going experience IAS.

What you actually get
Slow speeds - from 5mph to 37mph, reduced turning turning circle by approximately 1m / 3.28ft in comparison with vehicles without rear axle slip angle control (HSR)

High speeds - from 37mph and up, directional stability while driving and changing lanes


THE LONG LONG LONG INTEGRAL ACTIVE STEERING EXPLANATION

Electromechanical Power Steering with Variable Rack
There's a component that's a part of IAS that is very rarely discussed which is the electromechanical power steering system with variable rack (front axel) as well as the rear axle slip angle control (HSR).

The variable steering gear ratio in IAS is accomplished by the geometry/pitch of the toothed gear of the rack. Around the center position of the steering gear, the steering system behaves with steady directional stability. As the steering angle moves away from the center position, the ratio becomes increasingly more direct.



Variable Steering Gear Ratio Front axle




A) More indirect steering gear ratio in the center position of the variable rack (0° - 45°)
B) Transitional range (45° - 130°)
C) Direct steering gear ratio outside the center position of the variable rack (> 130°)
X) Steering angle in degrees
Y) Steering gear ratio in mm/steering wheel turn
1) Variable rack geometry (IAS)



Steering Angle of IAS on the Front Axle




A) More indirect steering gear ratio (variable rack geometry)
B) Direct steering gear ratio (variable rack geometry)


Rear Axle Slip Angle Control (HSR)




The rear axle slip angle control (HSR) mounted on the rear angle permits a maximum steering angle of the rear wheels of +/- 2.5°.

As a result, it was possible to reduce the turning circle by approximately 1m / 3.28ft in comparison with vehicles without rear axle slip angle control (HSR).

The rear axle slip angle control is available from a speed of approximately 5 km/h / 3 mph up to the maximum speed.

The request to adjust the steering angle at the rear axle is issued by the Dynamic Stability Control (DSC). A spindle drive inside the component is rotated via the electric motor. This produces a linear movement at the two track control arms. Using the position sensor, the control unit of the rear axle slip angle control (HSR) can determine the linear displacement and thus calculate the steering angle of the two rear axle wheels.

The spindle drive of the rear axle slip angle control (HSR) is self-inhibiting. This means that the X7 has the identical drivability to a vehicle without rear axle slip angle control (HSR) in the event of system failure.


SPECIAL NOTE WHEN GETTING ALIGNMENTS



A special fixture is required for alignment in order to assemble the carrier plates. For this reason, the carrier plates on the rear axle slip angle control (HSR) must not be undone. If this is not observed, the wheel alignment on the rear axle will become incorrectly adjusted.


Operation of Integral Active Steering




A) Opposite steering
B) Parallel steering

In the speed range up to approximately 60 km/h / 37 mph, the rear axle slip angle control (HSR) steers in the opposite direction to the steering angles of the front axle steering. This permits increased vehicle maneuverability.

As from the speed range of approximately 60 km/h / 37 mph, the rear axle slip angle control (HSR) steers in the same direction. This improves the directional stability of the vehicle.



Driving control interventions when cornering

When changing lanes quickly, all vehicles have a tendency to produce a significant yaw response and can sometimes start to oversteer. If the Dynamic Stability Control (DSC) detects a deviation between the driver wish and vehicle response, the vehicle is stabilized by means of a steering intervention at the rear axle. The speed of the stabilizing intervention is such that it is hardly discernible by the driver. It is possible to largely do without decelerating DSC brake interventions. As a result, the vehicle is more stable and the driving dynamics are preserved.

If the driver underestimates a bend when driving rapidly, he may be surprised by sudden understeer. The rear axle slip angle control (HSR) can also perform a corrective intervention in understeer situations and thus additional increases active safety.


Driving control on different surfaces
Hard braking maneuvers on roadways that are slippery on one side make the vehicle yaw to the vehicle side with more grip. In the event of emergency braking, the driver of a conventional vehicle must take corrective action. With this so-called µ-split braking, the Dynamic Stability Control (DSC) provides a stabilizing yaw moment via a steering intervention at the rear axle.





Further to A) Without DSC
When braking with a vehicle without DSC, maximum brake force is supported on the dry side of the road and only low brake force on the wet or icy side. An anti-clockwise yaw moment is produced which can lead to the vehicle skidding to the right.

Further to B) With DSC
When braking with a vehicle equipped with DSC, the brake forces at the wheels are metered so that the yaw moment acting on the vehicle is reduced. The vehicle therefore remains controllable. The stopping distance may be increased slightly.

Further to C) with DSC and rear axle slip angle control (HSR)
When braking with a vehicle equipped with DSC and rear axle slip angle control (HSR) (optional equipment Integral Active Steering SA 2VH), the DSC control unit calculates the steering angle for the rear wheels. The actuators of the rear axle slip angle control (HSR) convert the calculated steering angle into an active steering angle at both rear wheels. The resultant stabilizing yaw moment allows the maximum brake forces to be applied in order to achieve the shortest possible stopping distance. The perfect interaction of steering and brake intervention therefore increases active safety and enhances the driving dynamics of the vehicle.

[Wanderer73]

I won't attempt to give you an explanation at the level that Auricom blesses us with post after post

From my experience, the X7 without IAS handles very well for being a large vehicle (I've driven my friends many times). Equipped with IAS, the X7 gains a surprising amount of agility at low speeds. It snakes through a parking lot. At greater speeds on the highway, it almost feels like the X7 slides sideways into a lane change. It's a very odd feeling at first. There are other benefits outlined above, but those are the two that I notice on my daily drives. It's a great option!

[Phillymb75]

If you have to deal with tight spaces, it makes it much more manageable.

I park in a parking garage where we live with tight ramps between floors, I find it easier to drive the X7 through with the rear wheel steering than my M240 convertible. I almost never catch the rear tire on the turns in the X7, they have one of those ramp type ledges where you ride up on it if you don't cut it correctly, I'm at about 50% in the convertible. Mind you there is a 17 inch difference in wheel base and 28 inch difference in length between the vehicles...but that rear wheel steering does a lot to bring the back end around.

Just my example.

[xcountry]

Thank you Auricom for the detailed insight. It is very helpful.

One of my other cars is a 2017 Honda Civic Touring Sedan that has a turning radius of around 18 feet. In urban areas, this short turning radius is a blessing at times.

I read somewhere that the regular X7 has a turning radius of 21.4'. Does that mean that with the IAS, a low speed turning radius of 18.4' can be achieved? i.e. it will turn more or less in the same space as the much smaller civic? Thanks.

[xcountry]

Originally Posted by Phillymb75

If you have to deal with tight spaces, it makes it much more manageable.

I park in a parking garage where we live with tight ramps between floors, I find it easier to drive the X7 through with the rear wheel steering than my M240 convertible. I almost never catch the rear tire on the turns in the X7, they have one of those ramp type ledges where you ride up on it if you don't cut it correctly, I'm at about 50% in the convertible. Mind you there is a 17 inch difference in wheel base and 28 inch difference in length between the vehicles...but that rear wheel steering does a lot to bring the back end around.

Just my example.

Thanks for the insight. This is the kind of information I was looking for. One of my other cars is a Honda Civic and the two things I like about that are the 42 mpg fuel economy and the tight turning radius of ~18 feet. I known I can't get 42 mpg in the X7 but it seems that a turning radius of around 18 feet in urban areas can be achieved with IAS?

[xcountry]

Originally Posted by Wanderer73

I won't attempt to give you an explanation at the level that Auricom blesses us with post after post

From my experience, the X7 without IAS handles very well for being a large vehicle (I've driven my friends many times). Equipped with ISA, the X7 gains a surprising amount of agility at low speeds. It snakes through a parking lot. At greater speeds on the highway, it almost feels like the X7 slides sideways into a lane change. It's a very odd feeling at first. There are other benefits outlined above, but those are the two that I notice on my daily drives. It's a great option!

Thanks for the insight. I really appreciate it.

[Auricom]

Originally Posted by sjwr

Thank you Auricom for the detailed insight. It is very helpful.

One of my other cars is a 2017 Honda Civic Touring Sedan that has a turning radius of around 18 feet. In urban areas, this short turning radius is a blessing at times.

I read somewhere that the regular X7 has a turning radius of 21.4'. Does that mean that with the IAS, a low speed turning radius of 18.4' can be achieved? i.e. it will turn more or less in the same space as the much smaller civic? Thanks.

The standard X7 has a turning circle of 13m / 42.65ft.

IAS provides approximately 1m / 3.28ft reduction in turning for a turning circle of approximately 12m / 39.37ft.

X7 is still a 3 row SAV that's 5151mm / 16.90ft long with a wheelbase of 3105mm / 10.19ft

2000m / 6.56ft wide with a front track of 1684mm / 5.52ft and rear track of 1705mm / 5.59ft

LOL X7 will never turn as a compact as a Civic.

[xcountry]

Originally Posted by Auricom

The standard X7 has a turning circle of 13m / 42.65ft.

IAS provides approximately 1m / 3.28ft reduction in turning for a turning circle of approximately 12m / 39.37ft.

X7 is still a 3 row SAV that's 5151mm / 16.90ft long with a wheelbase of 3105mm / 10.19ft

2000m / 6.56ft wide with a front track of 1684mm / 5.52ft and rear track of 1705mm / 5.59ft

LOL X7 will never turn as a compact as a Civic.

Thanks for the additional details.

My 2017 Touring Civic has a turning circle of 36 feet. The newest 2021 Touring Civic's turning circle is 37.4 feet. The newest 2021 Touring Accord's turning circle is 39.6 feet.

Given X7's dimensions and capabilities, a 39.4 ft turning circle for something that big is still quite impressive in my opinion.

[Wanderer73]

Aggregate discussion translation = you'll be glad you optioned IAS

[sahajesh]

Originally Posted by Wanderer73

Aggregate discussion translation = you'll be glad you optioned IAS

Agree.

For me in the U.K., the current X5 is a big car and I'm glad I chose IAS (on the basis of the salesman giving decent and honest feedback, rather than YouTube reviewers who only drive the car for 30 mins).

[MashinBenzin]

I've driven 48 hour test drives in both a X5 30d and a X7 30d (uk models). The X7 had IAS, the X5 did not. Both were benchmarked against the Land Rover Discovery SDV6, but why I chose that each time is irrelevant here.

I didn't love the way the X5 drove. The X7 with IAS was a different kettle of fish and had an agility that belied its size. Carving around roundabouts and sweeping bends it was much better than the X5 and probably preferable to the Disco.

Tight slow 90 degree corners I didn't notice the IAS influence, but I am guessing that it was actually making a big difference as again the X7 didn't feel as unwieldy as I'd have expected from a 5.15m car on our tight roads.

TL;DR - I would tick the IAS box every time, without hesitation.

[xcountry]

Originally Posted by MashinBenzin

I've driven 48 hour test drives in both a X5 30d and a X7 30d (uk models). The X7 had IAS, the X5 did not. Both were benchmarked against the Land Rover Discovery SDV6, but why I chose that each time is irrelevant here.

I didn't love the way the X5 drove. The X7 with IAS was a different kettle of fish and had an agility that belied its size. Carving around roundabouts and sweeping bends it was much better than the X5 and probably preferable to the Disco.

Tight slow 90 degree corners I didn't notice the IAS influence, but I am guessing that it was actually making a big difference as again the X7 didn't feel as unwieldy as I'd have expected from a 5.15m car on our tight roads.

TL;DR - I would tick the IAS box every time, without hesitation.

Thanks. This is very helpful. I already ticked the IAS box and will know on April 30 how its like in person.

[xcountry]

Originally Posted by Wanderer73

Aggregate discussion translation = you'll be glad you optioned IAS

That's good to know. Thanks.

[ComingInHot]

You won't regret it . On daily drives it makes the vehicle feel more nimble and when you turn at low speeds you will be pleasantly surprised how quickly it maneuvers. I've driven both with and without and it is noticeable. Try doing a 180 degree turn in a tight area and you will see the difference.

[xcountry]

Originally Posted by ComingInHot

You won't regret it . On daily drives it makes the vehicle feel more nimble and when you turn at low speeds you will be pleasantly surprised how quickly it maneuvers. I've driven both with and without and it is noticeable. Try doing a 180 degree turn in a tight area and you will see the difference.

Thanks for the insight.

[like2short]

Originally Posted by sjwr

Thanks for the insight.

Originally Posted by sjwr

Thanks for the insight.

We have it on ours and it makes it much more nimble doing U turns, make tight right turns at intersections... highly recommended

[hudsonX]

I've been agonizing over this issue as well. After my test drive on a non-IAS X7, I felt unsure about even getting the car - turning out of the dealership, I could just feel how wide the turning radius was going to be. Living in Manhattan, it felt like IAS would be a game changer with such a large car, but I couldn't find a lot on the internet singing its praises, with some chatter of IAS making the car feel strange, which I would hate to do. My sales guy talked to one of the techs at the dealership, but the answer was unhelpful (basically just said it's a preference, not a good or bad thing). But sounds like it really does make a positive difference, so I'm going for it!

[huskerdoc2020]

Originally Posted by newbie2000

I've been agonizing over this issue as well. After my test drive on a non-IAS X7, I felt unsure about even getting the car - turning out of the dealership, I could just feel how wide the turning radius was going to be. Living in Manhattan, it felt like IAS would be a game changer with such a large car, but I couldn't find a lot on the internet singing its praises, with some chatter of IAS making the car feel strange, which I would hate to do. My sales guy talked to one of the techs at the dealership, but the answer was unhelpful (basically just said it's a preference, not a good or bad thing). But sounds like it really does make a positive difference, so I'm going for it!

Dude, it's a no brainer. Small price addition to the overall cost.

[hudsonX]

Originally Posted by huskerdoc2020

Dude, it's a no brainer. Small price addition to the overall cost.

Totally - I'm not worried about the cost, I just want to make sure my drive experience isn't inadvertently degraded with this thing...

[Auricom]

Originally Posted by newbie2000

Totally - I'm not worried about the cost, I just want to make sure my drive experience isn't inadvertently degraded with this thing...

It doesn't, if not it'll improve your driving experience. TBH what drivers mostly notice are the chances in variable steering ratio or IAS steering but the majority do not and doesn't take long to get accustomed to.

[huskerdoc2020]

Totally makes it better all around.