Yes I can be like that, having MS doesn’t help !
Ambient temps, whether hot or cold can really impact on people with MS.
Its called the Uhthoff phenomenon.
A variation as little as 0.5 degrees F can start things going bad.
You can’t argue with health. Especially in a situation like this.
Maybe that’s why most DS4 users don’t have such experiences and observations.
Yeah, I was just wondering if my DS was doing something different to others ?
Going on past experience it wouldn’t surprise me. 
But at the moment it seems to be performing as it should.
And may it stay that way for a long time.
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Another quick observation.
The ICE doesnt stay running.
For example, if you set the heater to lets say 24 with the car in hybrid mode, and the car hasnt been run and the cabin is cold, the ICE will start up , however, as the cabin warms up the point at which the ICE restarts is dependant on the cabin temp, if its cosy warm the ICE may not kick in until the cabin temp drops.
If ICE is running with the setting at 24 as an example, and you drop the setting to say 16 the ICE knocks off as its not needed to help draw in cabin heat..
So from what I’ve observed, this starting of ICE seems to be a back up to the heating system and depending on the temp of the cabin and the temp you ask for on the heater setting, so the colder the cabin to start with and the higher the temp you initially demand will be a factor in whether the ICE is started or not.
It also just kicks over at 1400rpm initially and then drops to 800rpm when cabin heat is demanded .
At these rpm’s ICE is doing nothing apart from helping out with the heaters, you can see this clearly as theres no gear selected, and the display shows all drive is supplied by the traction battery, unless of course you accelerate past “eco”, and the rpm’s will increase and gears engage.
I think I’ve sort of sussed out how the system works.
A little while ago I couldn’t work out why I was seeing these rpms at 1400 and dropping to 800 but not being used to drive the wheels, so looking back now it must of been that the heaters were probably calling on the ICE to help out ?
Is all DS4 no matter country/region equipped with a heat pump?
I know that my car has one, it is as I understood it fully electric and should be able to keep cabin temp comfortable well below -15c = ni need for the ICE to help.
But all DS cars are apparently unique or individuals 
I’m not sure what type of system the DS has or how it functions..
But after playing around with mine for 2 days I can see that the ICE starts up if the car is in hybrid, the cabin is cold and the demand temp setting for the cabin is set above highish, but the ICE does switch off by itself once the cabin has warmed up, in fact I didnt notice it coming back on once the cabin had warmed up.
Perhaps outside temp might also be a factor ?
So my guess is once the ambient temp in the cabin is within the demanded setting range on the heater or close to it, the ICE switches off and then leaves the heating system cope and to do its thing.
It’s like the ICE just helps it along if the cabin is too cold and the demand is highish, if that makes sense.
Running in full pure electric the ICE stays off, no matter what the heater demand is set too.
So one more observation.
This morning was very cold, with the car frozen over.
So after toying around with the heaters in hybrid mode over the last few days I thought I would pre-heat the cabin the old fashioned way this morning without using the cars the “pre-condition” feature.
Basically start the car put it in hybrid mode and turn the heater up to 25 degrees, the ICE started straight away at 1400rpm and then ticked over at 800rpm, I let it sit for 5 minutes minutes on the drive warming the cabin nicely before driving off.
When I drove off the ICE stayed ticking at 800rpm but the traction battery was driving the wheels, I slowly dropped the heater down to 17 degrees, at which point the ICE knocked itself off.
I then slowly increased the heater back up to see what happened, at 27 degrees the ICE re-started and knocked back off by itself when the cabin had warmed back up.
In my mind the ICE definitely supports the heating system if there’s a big difference to actual cabin temp and the requested temp set point on the heaters..
I found the trigger point at which the ICE starts up if in Hybrid mode is if the heater setting is around 23, 24 , 25, degrees, and switches back off if I dropped the setting to around 17 degrees, but this might be different in other cars ?
It also switched off once the cabin reached the desired temp set on the heaters, but didnt come back on at all, so my guess is once the cabin reaches the desired temp or close to it, the car then lets the heat pump cope ?
Just a guess ?
Sorry, I do understand, I don’t like the cold, but find a setting of 25 too hot.
I like the cabin preheat on mine, remember mines a Citroën, but when you preheat the cabin, the steering wheel is heated as well…loverly!
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I need to investigate the heat pump. It probably works when the A/C is on. But now I drive with the A/C off all the time and the heating works.
I work with automation/control, and trying to build a mental map of what the behaviour of the car’s logic is going to be very hard - it is clearly complex and trying to optimise all of the resources, and it would be too much to describe every aspect in the manual. The problem is trying to understand if something observed is normal or a fault (we read these all these posts so we probably expect a fault, and with your experience so far Jactag it is understandable !).
I had my car on precondition this morning - still enjoying the novelty of that. But today when pressing Start it went straight into Hybrid mode with the ICE running even with a decent charge in battery - normally it just starts in Electric only. On the drive back this evening, started in Elec only mode. The only difference this morning was colder (-5degC compared to -2degC yesterday morning when car started in Elec only mode) - I’m not too bothered about trying to understand as I can imagine there is some plausible reason for that logic based on ambient temp / load on the cabin heating. I guess if it started doing things inconsistently or seemingly wrong, then I’d want to understand a bit deeper.
if theres charge in mine it always starts in electric mode.
I have to select hybrid and turn up the heat setting for it to start the ICE
As long as there is no message “electric mode unavailable” at start there is nothing to worry about.
There was no warning (I did get that a few times when I first got the car, but it never reappeared, so assume it was just from the car being unused on garage forecourt). But I was just making observation that it behaved differently this morning, and probably due to some unusual set of conditions (ambient temp, AC settings, 12V battery, etc) that meant the logic in car started in Hybrid rather than Electric - but everything seemed to function fine and it started in Electric on way home, so all is good.
If i’m not totally wrong, i assume that with or without heat pump the electric cabin fan runs on 12V battery.
Then, when using preaheating without charging and car is only used for shorter travels the 12V battery is drained over time (multiple preaheating cycles and short travels).
If that description fits your use it might be a probable cause?
This happens to me when I unlock the car and wait a while before driving. That’s why I start driving as soon as I get in, because then I’m always in Electric mode.
One thing I’ve noticed over these last few days is when the heaters are on and the car is NOT running the ICE, the hybrid battery does drop quicker than when the heaters are off.
The ICE only runs (at least this is what I’m seeing), if the cabin temp is very cold and the heater is set above 23.
Once the cabin temp is achieved the ICE knocks off, but that’s when I tend to see the hybrid battery level drop a bit more than usual , so I guess the heat pump is then taking power from the hybrid battery to hold the cabin temp ?
The process I’m seeing with a cold cabin and temp set on 23 or higher is this :
ICE starts up at 1400rpm then drops to 800rpm, it stays at 800rpm until the desired cabin temp is met, then the ICE switches off, the heat pump then holds the desired cabin temp, all of this only happens in hybrid /comfort mode.
Its at that point I see more drainage on the hybrid battery than usual, so from that I assume the 12v battery does not run the heaters , but I may be wrong ?
When the ICE is not running, the source of power (instead of the alternator) is the traction battery. This provides a voltage of 14.7V in the 12V system, while simultaneously charging the 12V batteries. Without this, the voltage would quickly drop below 12V in electric mode.
So the heaters are run off the 12v battery if ICE is not running, but the traction battery then charges the 12v battery when the heaters are running.
Is this why we can see a higher drop in charge levels on the traction battery when the heaters are on ?
Does this also apply to the A/C (set to hot or cold ) ?
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The traction battery always charges when the ICE is off. It doesn’t depend on what you run in the car.
The 14.7V voltage in the 12V circuit doesn’t come from the 12V battery, because it can only “produce” 12.7V at most.