Auto speed limiter fault

[MikeMacan4S]

Our Macan EV 4S has a useful Auto Speed Limiter which adaptively sets maximum speed to the road speed.
It is a great feature which ensures you don't exceed the speed limit.
However, it often sets a speed which makes no sense and is dangerous.
A common one is on a motorway it can suddenly switch from 70 mph to 30 mph and forces the car to brake hard. If a car is behind you and you dont flip the feature off quick enough you could be rear-ended.
Today it changed to 80 mph in a 30 mph area. This is bizarre as 80 mph is not permitted in the UK.
I thought it was picking up false info from signs but I havent seen any when this has happened.
What can I do about this?

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[Awaz]

Auto speed recognition is a problem with Macan, more so in the UK.
There are some threads on this issue already. Here is one of them:

Speed Sign Recognition for Cruise Control - Anyone Still Having Issues? (UK users in particular) | Macan EV Forum, News, Info - MacanEVowners

 

[Wivenhoe]

The easiest way to overcome the issue is to turn it off. As Awaz says, there are a lot of posts on here about the issue. It is a combination of things - the wrong limit in the Sat Nav (Porsche has known about this for over a year), the cameras picking up some slip roads with limit signs, signs covered in foliage.

 

[W1NGE]

Our Macan EV 4S has a useful Auto Speed Limiter which adaptively sets maximum speed to the road speed.
It is a great feature which ensures you don't exceed the speed limit.
However, it often sets a speed which makes no sense and is dangerous.
A common one is on a motorway it can suddenly switch from 70 mph to 30 mph and forces the car to brake hard. If a car is behind you and you dont flip the feature off quick enough you could be rear-ended.
Today it changed to 80 mph in a 30 mph area. This is bizarre as 80 mph is not permitted in the UK.
I thought it was picking up false info from signs but I havent seen any when this has happened.
What can I do about this?

Sane story on all Porsches with this feature and has been so for many years.

I experienced it on my first Taycan in 2021.

Relies on accurate mapping and signage data which in UK can be a lottery. Road works are a particular challenge if there is no end of a speed restriction detected.

Not a fault.

Turn it off.

 

[MikeMacan4S]

If this feature caused an accident, potentially with fatalities, the judge is not going to say 'This is not a fault. You should have turned it off".
It is a serious issue for Porsche and it is cured by making the software deal with this case intelligently when it arises (whether it is trees obscuring signs or any other reason).
So. For example. It wants to change your speed to 30 mph on a motorway. The software should know this is is dangerous and check its inputs again, or flash a message before slamming on the brakes. Yes?
Similarly, it should know that if you are in a 30 mph area, it makes no sense to let you speed up to 80!
This is not a difficult problem to solve
Porsche should do it before someone gets killed.

 

[Wivenhoe]

I think you would struggle to convince a judge that Porsche are responsible for poor signage in the UK. I feel sure the judge will point you to the warning words that Porsche tell you about the potential failures in the option. He would also point out you the driver are responsible for driving the car.

The problem for the manufacturers is that they buy in, so don’t control the data, in the Sat Nav. Then you have temporary limits, none of these are in the Sat Nav and local authorities slapping on 20 mph limits overnight, no Sat Nav database can deal with that. So cameras are used but then they are wholly dependent on good signage - UK is crap at that.

The only reason to use the auto speed limiter is to avoid fines. The safe way to achieve that is to use the manual speed limiter which is reliant on you rather than cameras to get the right speed limit.

The UK is allowing self driving cars, so you now know not to follow them too closely.

 

[W1NGE]

If this feature caused an accident, potentially with fatalities, the judge is not going to say 'This is not a fault. You should have turned it off".
It is a serious issue for Porsche and it is cured by making the software deal with this case intelligently when it arises (whether it is trees obscuring signs or any other reason).
So. For example. It wants to change your speed to 30 mph on a motorway. The software should know this is is dangerous and check its inputs again, or flash a message before slamming on the brakes. Yes?
Similarly, it should know that if you are in a 30 mph area, it makes no sense to let you speed up to 80!
This is not a difficult problem to solve
Porsche should do it before someone gets killed.

The caveat on all assistance systems is written in the Owner’s Guide and elsewhere - operating conditions.

Road signage and road markings in UK are poor.

If there is temporary signage active and not properly in place then no system can make the correct assessment - ultimate control wrests with the driver.

System is off by default for a reason.

It's not just Porsche either.

 

[Awaz]

the judge is not going to say 'This is not a fault. You should have turned it off."

I disagree. On the contrary, the judge is going to say, 'as you have observed before, it behaves erratically; you should have turned it off. The driver is meant to be in control of the vehicle at all times. This rule applies to even FSD cars like Tesla!
As others have said here, "Turn it off." So have I, like others, especially in the UK, where this issue is more prevalent. I manually adjust speed limits, which is just a few quick flicks of the speed stalk.

 

[MikeMacan4S]

Interesting to read the replies to my posting about a fault that could be cured with software. Thank you!
Interesting that some people accept that it is OK to buy an extra on a car and then keep it switched off because it doesn't work properly and could be dangerous.
Good for Porsche to think that many customers will take the view that when Porsche get things wrong it is the customer's fault.
But, Porsche will have this on their list of things to fix, because they know that they would have a weak case if this issue causes a fatality with a customer who thinks that features they have paid for should work and not be dangerous.

 

[Awaz]

Interesting that some people accept that it is OK to buy an extra on a car and then keep it switched off because it doesn't work properly and could be dangerous.

The impression you have generally given from your first post onwards is you would rather continue to use this function even if it is erratic and blame Porsche; then the judge would be on your side if an accident results.
As mentioned before, there are many threads on this issue before where we all have been disgruntled about Porsche not getting their act together. I even mentioned in one of those posts that I never had this erratic speed recognition issue in my previous EV, the i4.
So, the options are, until Porsche gets its act together, do we keep using the erratic function or disable it? Clearly, most prefer the later!

 

[MikeMacan4S]

The impression you have generally given from your first post onwards is you would rather continue to use this function even if it is erratic and blame Porsche; then the judge would be on your side if an accident results.
As mentioned before, there are many threads on this issue before where we all have been disgruntled about Porsche not getting their act together. I even mentioned in one of those posts that I never had this erratic speed recognition issue in my previous EV, the i4.
So, the options are, until Porsche gets its act together, do we keep using the erratic function or disable it? Clearly, most prefer the later!

Not exactly. I would like features I have paid for to work.

 

[Awaz]

Not exactly. I would like features I have paid for to work.

We all do. You are not alone in this.
If you read the other threads, all those who have been affected have complained about it here as well as to Porsche (or most have). As when I took the car for the software update, I mentioned it and was told it would get better after the update. It never did!

 

[W1NGE]

Interesting to read the replies to my posting about a fault that could be cured with software. Thank you!
Interesting that some people accept that it is OK to buy an extra on a car and then keep it switched off because it doesn't work properly and could be dangerous.
Good for Porsche to think that many customers will take the view that when Porsche get things wrong it is the customer's fault.
But, Porsche will have this on their list of things to fix, because they know that they would have a weak case if this issue causes a fatality with a customer who thinks that features they have paid for should work and not be dangerous.

Active Speed Limit Assist is not an extra and is standard on all Macan EVs (can't confirm if from 2024 or only from MY 2026 (late 2025 onwards)).

When activated and the car powered off then on again the system default is a passive mode (greyed out) and available should you wish to invoke. This will be due to an EU ruling no doubt like much / all of modern car ADAS systems.

Dealership blarney is generally to be ignored as they are generally the least likely to be informed about this level of detail. Gold Techncian might be a better source at your dealership.

I've already mentioned that it's been an "issue" or "feature" for many years and if solvable would have been addressed long before now.

What is interesting however is that some folk prefer to ignore the conditions under which technology such as this is designed to work and what the inherent dependencies are. Needless to say even fewer actually read the supporting documentation to better understand the operation and limitations.

If not familiar with the iconography see below for what they are (grey means passive (ready for use but not active), red if the driver must take over, green for go etc.

 

[MikeMacan4S]

A speed limiter is a simple feature on many cars. By making it adaptive to the current speed limit makes it much more useful.
When the small print says be attentive, it is referring to normal hazards, like someone stepping into the road in front.
A normal user would not expect it to mean "If the system suddenly brakes your car from 70 mph to 30 on a motorway, and you have no time to switch this feature off, and as a result a lorry runs into the back of you and kills your family, then this is the fault of your inattentiveness."
All the small print in the world wouldn't win this case for Porsche if it went to court.
The public should expect safety systems to be safe.

 

[W1NGE]

A speed limiter is a simple feature on many cars. By making it adaptive to the current speed limit makes it much more useful.
When the small print says be attentive, it is referring to normal hazards, like someone stepping into the road in front.
A normal user would not expect it to mean "If the system suddenly brakes your car from 70 mph to 30 on a motorway, and you have no time to switch this feature off, and as a result a lorry runs into the back of you and kills your family, then this is the fault of your inattentiveness."
All the small print in the world wouldn't win this case for Porsche if it went to court.
The public should expect safety systems to be safe.

It will never do this on a motorway unless you are speeding in contraflow, roadworks etc and the temporary limit exceeded.

Please don't fabricate improbable scenarios and do not be naive enough to ignore usage guidelines.

Note also that these systems are reliant also on various 3rd party data and physical sources - mapping, local contractors for roadworks and signage, councils for accurate signage and so on

How are you getting on with the Lane Keep Assist as it is terrible again due to UK road markings especially on B roads?

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