Colder temperatures hybrid system

[BROUWERS]

Since the temperatures have started to go down under 10 degrees centigrade, I've noticed I'm unable to drive purely electrically as much as I did before. Now, I've read about this and it does make sense to me, as it takes longer for the petrol engine to warm up and the heater is on. But even when I drive with the heater switched off and the needle on the temp gauge is somewhere in the middle, I've noticed the petrol engine to switch on much earlier. The bottom of the power meter shows some lines and I could always go up to the highest line before the petrol engine would switch on, whereas now it switches on halfway down these lines already. I've also noticed it continuously tries to switch to combined electrical/petrol driving at higher speeds but after a millisecond switches back to petrol only. Also when driving purely electrically, even in a car park, the center screen shows I'm using petrol still. 

It's my first winter in a hybrid so not sure what to expect, but I wanted to know if you have similar experiences.

By the way, ISC learning shows Complete in Techstream, so that's not the culprit here.

Thanks

[Zotto]

At low temp thermal engine is often on to stay at leas over 40° C,  but beside this the hybrid Battery efficiency and capacity is lower, so it discharges faster and needs recharging more often. Don't be worried about using petrol engine, it helps to have better mpg compared to intense use of electric traction, as HV Battery needs recharging before or after: the secret is to recover all energy you can in decelerations.

Said this, mpg in winter time get worse even not using heater.